i personally liked riku's more, it had character development that wasnt completely useless (ie he didnt forget), using darkness was a nice change, after kh2 "stupid sora" riku was a god send and also his fixed deck and fast reload.
with sora i just had like 3 main decks i used or was it two? one had the tornado sleight, it was set up so i could spam it over and over, i used this deck to clear rooms it made leveling quicker and easier and since i got it done quicker less repititve for me.
the other one was all attack cards (all the cards dont go lower than 7) with bout 3-4 zeros' and 3 cures at the end so i could heal quickly. the only boss cards i added to it are usually vexen, might use others but i cant remember. i use this deck for boss battles.