I suggest giving one a few runs, then read up on scoring strategies for it, then give it a few more runs with what you've read in mind, then re-examine the scoring strategies and give it a few more runs.
Do this with all the game you have, and then decide which one you think is the overall most fun to score in. I would wager that you'll never be the world's best player at any of them, so just pick the one you like most and then play it as often as possible. If you get sick of it, switch to a different game and let yourself recharge. There's no correct answer for this, it's whatever YOU like best. Keep playing, and try to best your scores.
Other than that, it may be a good idea to stay away from Guwange and EspGaluda II for now. Guwange has an extremely strict system, where one death can really cost you. EspGaluda is insanely in-depth, and might be too immense to start out with.
But if one of those is your absolute, no-nonsense favorite, then by all means, go for it. Just try to have some fun with it.