Oras or usum. I like oras a lot and I play it over the gen 3 games if I feel like going through hoenn again. Nearly everything they removed was minor and didnt bother me and seem like mostly nitpicks. They added a ton of awesome shit like dexnav, soaring, elite 4 rematches, phys/spec split, fucking fighting deoxys in space. I thought they were good.
Usum is a contender because aside from some lagging during battles they looled great. The world was bright and colorful and the character designs were really good. Totems were fun and challenging and they gave lots of trainers good ivs and even EV spreads for the first time. If you domt use xp share or pokemon refresh, and dont EV train in game theyre by far the hardest games. I wiped more to them than any other.