What is the longest you have stuck with a particular main as your main?
My longest runs were from my Shaman and Druid. Shaman was from BC and lasted as my main up through Cata. The Druid took over in MoP and has remained my most played character although I wouldn’t consider any of my characters worthy of the title “main” anymore.
If I were half decent at DPS my warlocks would probably be up there… 
this gentleman here has been my main since wrath and i don’t see that anytime soon
Hunter. From Ulduar in wrath to some unknown point in time. Depending on when you want to call the end, it could’ve been until ToT in MoP when I first quit, could be until about 6 months ago when I stopped playing again, or when the servers shut down for good since that’s the only time I’m guaranteed to never play this game again in my life.
Been maining my mage since 2005. Don’t think I’ll ever change that at this point.
Aff lock, played since vanilla. Have never changed my main. This expac I’m not exactly getting rid of my lock as my main, but I’m having it for pvp and a resto shammy for pve.
1 expansion. I mained holy paladin through all of Cataclysm. All other expansions I either changed mains per raid tier (from Wrath onward), or ‘double mained’ – 1 Horde, 1 Alliance (Vanilla & BC… I wasn’t a raider, just those were the two characters I concentrated on).
shadow priest. from wrath til now save rogue in wod
Mage is another class that, if I weren’t terrible at DPS, I wouldn’t mind playing as more. The teleports to ever expansion are tantalizing.
This girl has been my main for eight ish years now. I started her within early MoP, no plans to ever change her.
Was hunter rogue in vanilla till TBC. Then became DK from Wrath onwards. Might main this monk in SL though 
Vanilla was a mess for me. I probably level like 30 characters with most never getting past 30. I only got two to 60 a week or two before BC came out. 
This exact character since Cata, though I did raid 25 man on him in wrath as well
This character has been my main since Cata when I rerolled on Proudmoore.
My other hunter now on this realm was my main from Vanilla until Cata.
<----- From the beginning of it all.
I clearly need to stick to a few characters if I want to get anytime done
Surprised to see so many keep thier mains so long.
I’ve mained my druid exclusively since wrath.
<----
Since Oct 2008
My pally. From vanilla til the bfa pre patch in legion. Then I went full on orc warlock.
This priest since Wrath. Haven’t change the main spec, nor her hair since she was created. 
(Though I may switch main in SL… still thinking…)
Kind’ve a toss up for me.