Evony is a mid-quality city-building PBBG.
Unfortunately, the administration (i.e. GMs and Mods) are possibly worse than those of Gameforge. I would not recommend it.
I recommend
The Lost Castle (single-player)
CitiesXL (this is retail)
Heroes of Might and Magic III (Free, yet requires knowledge of how to emulate DOS using DOSbox)
Star Peace (the first true MMO city-builder that I have heard of --> now bankrupt)
And then there are like crafting-RPGs where you build structures (Tale in The Desert, Universal, WURM, etc.).
Hmm. And then there is just strategy, like Battle for Wesnoth. This has a high-emphasis on PvP (and the PvP is well-balanced).