Triple Triad will always be my favorite cause it had the most thought put into it and it follows the correct formula for a successful game.
1) Easy to Pick up
2) Difficult to Master

That's not to say I didn't absolutely enjoy the submarine game and snowboarding games in VII. I also like Chocobo Hot and Cold (though the sword fight scene in the opening of the game is still my favorite ). The breeding was okay but it does get tedious.

I also really enjoyed Sphere Break, which surprised me cause I hate math but damn if I wasn't good at this game. It's one of the few things I did like from FFX-2 (the minigame mecca of Final Fantasy).

Blitzball was horrible (Tallulah says it best) the game is just not balanced well enough to keep my interest. To this day, Wakka is still the only character I was unable to acquire his ultimate weapon cause I couldn't bring myself to enter another damn Blitzball game.

Ultimately, my least favorite minigame in FF is actually Tetra Master. The rules are complexed and just seem random rather than thought out. In the end, games are decided on who goes last rather than an actual strategy.