If you have decent situational awareness, you can do well as a frost dk. We get kills kbs and top damage no problem, and with heals we're amazing. Without heals, well geared ferals and rogues and sometimes warriors will eff you up. If your concern is going for the win and rolling with the group though, you are making a great choice; howling blast spamming flags in AB and Gilneas is amazing. The spammable aoe snare is also amazing.
Make sure you get the addon Healers Have to Die, as a frost dk you can be a serious threat to enemy healers (which is why I'm blood elf for the silence, every bg I make it my mission to make the enemy healers as miserable as possible). Plus doing this will net you more hks, as the old sang goes the fish rots from the head; when you kill the healers you ultimately net yourself more hks as you will prevent the healers from healing up their team so their team dies around them. And with necro strike spam, you can be the best healer killing class in the game.
If you roll a dk and adopt my random bg mission make sure you download the addon DDR or something similar to display your runes, and make killing healers a sort of minigame of it's own, it's really fun as a frost dk :D purple bars up? spam necro strike, blue bars up? spam howling blast for runic power to frost strike and get those yummy killing machine crits, then more necro spam. It's a fast paced and somewhat robotic playstyle. The drawbacks is it can get mind numbingly boring after a while, but it's a great spec to play when you don't want to do much thinking and strategizing kills. Copy my spec and glyphs also and you will be a healer killing machine :D
So, imo, the best class for hks is the class that can pressure healers the best, and frost/unholy dks come second to none.
TL;DR frost dk for killing healers thus getting more hks and also for winning with hb spamming flags/groups (which also nets kbs), also frost dks are frequently on top of damage charts if that's your thing. Drawbacks are against most melee you're screwed if you don't have heals as your mobility and melee survival cds suck therefore is not completely self reliant.
And death grip, OMG. Every time it's up, you pull someone into your group and you just got a free hk, and if you get the killing blow you can do it AGAIN :D Just this ability alone is worth rolling this class for your goals. It has so many uses...
Edited by Scarlët on 10/12/2011 10:56 PM PDT