What genre is easy to play on acoustic guitar?

Folk music and pop music are the easiest. Your best bet is to get lessons with a professional guitar teacher and he'll assign songs to you. Good luck!

Some of the classic folk or country songs will probably be the easiest. Start with slow or moderate tempo. "Where Have All The Flowers Gone" (G-Em-C-D) might be a good choice, if it interests you. "Wagon Wheel" is pretty easy.

More importantly, you should practice changing chords. Just do some exercises where you either use a metronome app or tap your feet and change back and forth between two chords. For instance G → C → G. Start as slowly as you need to go without making mistakes. The idea is for your muscles to memorize the *correct* motion so that they can remember it. Once you develop "muscle memory", your hands will automatically know where to go. The only way to do this is repetition...aka practice.

There are certain chord combinations that you'll commonly see together, and you should focus on those to begin with. Here are a few:

G→C

C→D

D→G

A→D

D→E

E→A

Here's a video I made a few years ago which shows a few tips for quickly changing between chords:

https://www.youtube.com/watch?v=cetrqYqQ470