So I'm interested to know what everyone's favorite combo is.

Mine is the Jack lvl 3 + Hercules lvl 3 + Parasite Cage combo.

Destiny islands to find Jasmin to get lvl 4 aladin, then play donald lvl 1 to play bambi lvl3, draw two cards, then play aladin and get the showtime genie, to find simba lvl 3, play him, get rid of bambi and Jasmin and two of the opponent's friends, then Challenge with 22+ attack (riku lvl3 [+7]+ simba lvl3 [+7]+ genie lvl 4 [+8]), and my deck is down to 28 cards on the first turn :)

simba lvl4 cast by a high magic guy keep that high caster then follow up with simba lvl1 bam they are out of friends

These two aren't really viable in the current meta...but some of my favorties are:

Play Moogle. Drop tons of high level friends. Challenge with Moogle. Fairy Harp it. (Also known as "The Moogle Harp" Combo)

Abu + Pinnochio

stopga + hundred acre wood

simba 4 + gravity or simba 1 + pot spider

jasmine + aladdin 4 + genie 4 + magic lamp. lol ive only done this twice but it was great both times

and of course destiny islands + level 0

i do like the jack + beast/herc combos too.

Tidus their Owl+Simba lvl 3 when monstro is out, man it never gets old