The swingfire
Back in the distant Stone, or rather Obsidian-Age, when Swingy was tier 4 I think, I absolutely loved it. And I played it all in PvP, when I still bothered with pvp.
I loved it so much, it was the first tank I paid actual IRL money, to buy some camouflage for.
Then they shoved it up a couple of tiers, made it handle like shit, and generally made it into a really good way of losing and dragging your team down with you. Because anyone could just drive up to you, and the minimum missile range meant you were dead, because you had NO Weapons, no armour, and couldn't even run, because it was so slow, and unmaneuverable. In other words, they completely ruined it. 
And I haven't played it since
Now you've intrigued me, I might have to try it out again...