I already have 3K vanilla, which I like, but I'm curios if 2k is in any way better. It's been so long since I've played it.

The core gameplay is very similar.

2k lacks garbage, neighbor deals, special offers, probably a few other things. Personally I prefer 2k, on account of the style and a tighter focus on that core gameplay.

Does 3k have arcos?

There are probably quite a few details in terms of development and transit that I'm not aware of. 2k does have problems with the services, in particular with fire, education, and health not needing to be placed near the rest of the city, or even funded in the case of fire.

Two words: Launch Arco.

SC2K has less 'micro' to worry about, which I think has made it a lot more enduring for me - it's easy to plan a city and make it happen, without worrying about landfills and the like. And (I may be wrong, I didn't spend much time with 3k) SCURK was really easy to use to customize building sets.

If you have 3k dont bother with 2. Its the same game with less features

I prefer 2. It's a better "core" game, as mentioned earlier.