Merging with this other music thread - probably don't need another one to discuss which ones you like the most.
I need to hear more before deciding which ones I like the most, but I sure do have a number of favourites though. The Rival and Gym Leader battle music was great, along with the Ho-oh battle music and Kanto battle music, Eusine's theme music, the Champion music... while places like National Park, the Lighthouse, Tin Tower, Route 27, many of the Team Rocket themes, Dark Cave ... I suppose I could go on for some length. XD A shout out to the credits music as well.
There are a few tracks that aren't as impressive, but I think I just have to listen to them some more before I can really enjoy them, is all - for instance, Dragon's Den seemed to sound a bit odd at first but I quite like it now after a few listens. One must remember you can't always enjoy a song right off the bat. (And of course, not everyone is going to like the same as everyone else and obviously not every song is prefect).