I do feel the tech points need to be upped on Synesia simply because Arboreus does not need walls, so they get a "free" point. Also, architecture should just be given at rank 5. All cities will need it and seems rather punishing to make every city waste a point on it.
Now, a perspective on someone who has had to maintain a city in each incarnation: The current incarnation is brutal for cities. While the lack of tech progress has made people simply put down a house wherever and limited the income of the cities, for several tests there has been no real incentive to, or desire by, the players to help build the city. They can simply plop a house down and get the benefit of the city. The decrease in harbor funds has hurt. We used to help foster the economy by putting out buy orders and selling items. No income means no city progress. We are literally begging people to help progress. I know the lack of tech tress has made it easy to ignore the pleas for city growth, but even when we did have the trees it was a challenge to get people to fork over money to help. And that meant it was usually done by a few. There needs to be some incentive/mechanic for players to pitch in.
Taxes: Taxes on crafting should be a minimum of low. There should be no option for no taxes or it's a race to the bottom. For the most part, players don't care about what it takes to keep the city going so they only look at the tax rate. If there is none, whomever reduces them to 0 gets the influx of people at the long-term cost. This not only hurts the city but eventually hurts whomever builds around said city as it eventually goes into decay as a small group of people give up on trying to make it work. I would like to see a mechanic where one must be a citizen to buy land, partially because there is no real reason to be a citizen anymore and partially because I would like to see an "income tax" implemented. This would mean that changes would have to happen to automatically split all gold in a group (or at least within range) so that a small portion could go to the city they are a citizen of. Such a change would provide cities with a steady income and incentivize them to help citizens gain power as well as organize groups to hunt.
Other city income: Allow cities to create buy and sell orders on the market for the city. They could be stored in, or taken from, storage areas. Right now there is no use for the storage plots since they don't hold much and it is just time consuming to put items in, just to take them out again. Using the market in conjunction with the storage areas would greatly help with the city, the players (they can buy raw materials from, or sell to the city) and grown the economy. The same idea could be used for other items sold and the money goes right to the coffers. I know this next part is somewhat of a large rework, but the city could supplement the crafting taxes if they wish, for the city build workstations, or even the private ones in citizen's homes. So a city could allocate X gold per craft paid by the city if they wish. The idea is to get the citizens some return on the income tax and encourage people to stay. Why not just not collect taxes? As stated, such settings leads to a race to the bottom and all cities end up hurting. This should be a conscious decision and based on how well the city is doing. The more you can tweak an economy, the better it is as the game progresses. The best options for the economy are not the same for early game as later game. They need to be adjusted as the player base varies.
Farming: On a quick note, the farming plots drive me crazy. They are just bigger than one square. This makes it very difficult to plan and farm. Reducing the size to one square allows more efficient use of the land and prevents the movement of plots by a small amount to regain fertility. I would also like to see players be able to plant small plots. Since the housing squares are 1/4 the city squares, have them provide 1/4 the growth. This allows players to grow and sell food to city, helping the city as a player and making some money. Since cotton has a use now, players will want that, but the crop rotation will require other crops too. Getting players invested in the city where they live will help with the economy as well as being invested in defending said city.
City defenses: One thing that has bothered me is that the size of the city doesn't matter much when it comes to attacking or defending. The sides are equal. This means a city of 30 people could take on a city with 1000 citizens if they are coordinated. The balance of power goes to a group of griefers.
Citizen plots: People end up investing a lot into their house, only to find out the city goes under or they don't like where they live. To make the economy work, people need to be able to move, but not without cost. The question is, how much cost? Should they lose their entire inventory? Right now there is no way to move without simply destroying the house and everything in it. Maybe allow an overlap of 1 week where a person can have 2 houses, for a cost of course. This would allow them time to build a new house and move items from one location to another. Maybe the cost of a new plot in the new city plus 8000 as gold sink (12,000 total with default housing costs). With this addition, make the tax rates on all plots around town be in sync. If a city raises plot taxes by 1000/week, then it applies to all plots, nit just always 1/2 the initial plot cost. Again, this is to allow for economic changes as the game changes and allow cities to adjust income to provide services.
Services: Cities need more services they can provide directly to citizens. Maybe housing/player skins that cities can buy to provide all citizens. Maybe an ongoing cost to keep tech rank up. This would also help balance the tech tree issue. If each tech point had an ongoing cost, it would behoove citizens to help fund the city and not just rely on a few people to keep it going.
Recipes: Not directly a town in itself, but an idea here. As it is, recipes have a large value in the beginning then quickly fall in price as the demand for some/all falls off. The idea has been presented to do research to get recipes, but this only works if it uses something that will always be in demand, otherwise the same issue happens where the demand falls off and the price plummets. I might suggest using dust as the tool to do research. Since you use it in enchanting as well, the demand would always be there. In addition, each step in the recipe must be researched, so that higher quality would demand more research. This can be time gated to slow the process, but that really only applies in the launch stage of the game. Once enough people can make the items, it really loses meaning. The other option is to allow research of individual recipes, but the town much pay for the initial jump in quality level as well as an upkeep. This forces you to make economic decisions rather than just allocating points. It also allows players to decide what they want to spend their money on. They may have more options to craft, but higher taxes as a result to pay for upkeep. This could really go towards a town's uniqueness if we use some of Spoletta's ideas and have a massive tech tree where you can choose things like what essences you can create.
City permissions: there need to be some more granular permissions for cities and a choice about what those levels can do. You may want to allow some people access to workstations but not crops. Maybe someone needs access to crops but not smelters, or vice versa. Without that it forces city planners to be very careful with permissions as you give away the keys to the kingdom, reducing overall participation in the city development/upkeep. Maybe you want some players to have access to certain storage plots. Even going so far as limiting some people to putting items into storage/smelters but not take out.
Maintenance: Cities should require some raw items to maintain the city. Yes, as a person who does most of the city work, I kind of hate this idea, but it really needs to be done. The more buildings/Walls a city has, the more items are needed on a regular basis to keep them repaired. IT may be simply making sure there are enough of stone and wood in the storage areas and they are removed as upkeep. Otherwise walls may lose durability or workstations may not work if forgotten. Again, if the city can place buy orders for said items and deposited in storage it allows players who like to gather to make money and keep the economy going. The storage areas would need to store MUCH more than they do now though.
Settler group: I don't like the idea of lowering the city settler group to 5. We saw earlier where people would get a group of 20, found a city, then decide it was too hard and let it die. This really only hurt the people who built around the city, especially since they had no way to leave. Lowering that to 5 would only exasperate the issue.