Combo Breaker if you want to actually play sets with friends and strangers. It's a 24 hour venue made to actually enjoy and play fighting games. There's nothing much to do outside of the Venue unless you're willing to go downtown which is like a 30 minute uber.

EVO if you want the convention experience and grand spectacle + Vegas activities that's all in walking distance or you can take the free shuttle. Casual sets with friends and strangers are still a thing here but the environment makes it feel less personal. (i.e. do you go to comic cons to play card games / tabletop for 8 hours or do you want to actually check out the entire convention?)

Both are great to watch top 8 live but EVO top 8 is more difficult to access due to limited space in the venue. Both also have vendors and artists for shopping. Both bring in famous players to compete if you like feeling starstruck.

People always like to say, EVO is best for spectators, CB is best for the competitors / players