My dream list:
1. An elemental melee weapon set. Using the animations already present but you can set it so that it is fire, ice, stone, etc. I always like fire melee because of the 3 swords attacks and it would be cool to have a full set. Picking an elemental set also gives you the typical secondary effects so fire would be DOTS, ice would be slows, etc. I love the mallet from stone melee and hopefully it could be applied to that as well with maybe the Battle Axe melee set.
2. A whip powerset that is a bit like how claws is melee with some range. There are currently 3 animations for whip I think. So it may not be feasible to create animations for the other powers but having a hold power could be taken from the mastermind set.
3. It took me awhile, but I am beginning to like dual pistols gimmick of switching between ammo types. Staff, and bio also have different effect toggles. I would like to see that implement in older legacy powersets.