For me it was the ADS mount back when I was working on getting it- not healer specific obviously, but when I wanted to be sure to win and there weren't enough healers that made swap. Also when I'm on DPS I try and remind the alliance to commend the healers on their team (which I don't ask for obviously when I'm on a healer role, that's tacky, I only ask for that on behalf of others). Someone who's solo healing for their team and doing an effective job of it should be getting 6 commendations and faster progess towards the associated rewards... even if a team member had battle fever and got 30 kills... because they never could have done that without a healer keeping them up obviously.

Some healers are terrible and screw over their team by casting weak non-CS DPS abilities and they're the worst... if I'm a DPS with battle high I'd be safer with another DPS by my side than a healer who isn't healing me (this one idiot WHM who had me at 10% Hp while I had battle fever and was running back and forth next to them waving while they cast aero 3). But other work their ass off, like this one SCH the other day stone skinning everyone in sight while defending a node, or the one in the alliance who miraculously kept me alive when I hit some weird lag and every one of my abilities failed while I had 3+ people on me I couldn't defend against.