Hand Cannons with high Impact (the ones that have almost full Impact) need to have significantly increased range. Close quarters combat skill in the Crucible is essential on most maps (even some Combined Arms map areas) and the fire rate on large impact Hand Cannons does not cut it, almost ever. The super low fire rate these Hand Cannons have is viable only at range, of which they lack.
Auto Rifles need to be upgraded in the damage category slightly. Currently they do not compete, at any range, with all other gun classes in PvP, and are much too hard to use against enemies in PvE. For example, most of the Rare class Pulse Rifles, Hand Cannons, and Scout Rifles can still outgun Legendary and even Exotic Auto Rifles 9/10 times in Crucible. Even without the rarity system, Auto Rifles are outclassed in the Crucible and PvE alike when it comes to damage.
I don't you will get any love for wanting to buff any handcannons at the moment.
However, ARs need to be rebuffed, and I hope that is something everyone can agree on.