My Hunter is my first character and my main character. I am not sure if part of the reason I love being a Hunter so much is because it is the character I first experienced nearly everything in the game on. It was the character I was on when I first found new areas, did new quest and went through dungeons and raids with. It was the first I did everything with basically. Everything except heal or tank that is.
My Priest was my first healer and my Druid was my first tank, even if I did have a DK and a Paladin made before I made the druid. If I were to choose now to have three mains, a main tank, a main healer and a main DPS I would choose my Hunter, Druid and Priest for those three roles.
There is only one problem with that. Outside of my Hunter, Druid and Priest I only have one other 80 currently and that is a DK that I use as my bank character. I got the DK to 80 only so I can train up the new professions once Cataclysm comes out. I did not want to have to go back to level it later. I do not use the DK at all really. It is still in quest greens and has not been outside of a major city in months. Not even just to get a breath of fresh air.
I wonder if my opinions will change once I get the other characters to end game. I know from the few I have experience with that I have made decisions based on role already. Each class has inherent things they need to deal with and when in a group setting how they deal with them is different.
DPS - I have no problem with running dungeons with a DPS character. It takes longer to get into one and there is a lot of pressure to do huge numbers even more so in heroics then ICC it seems as funny as that sounds but over all most people do not give a crap as long as things are dying fast and you are not screwing things up to make it harder for everyone else. Gearing up a DPS player through dungeons might take time but it is actually pretty easy. I wold go with people I do not know because no one gives a crap if someone did only 1.5K DPS if the dungeon is done in 15 minutes and goes off without a hitch.
Healer - Every time someone dies it will be your fault. If the tank runs ahead and pulls a whole room while you and everyone else are still in the previous room, it is your fault. If a DPS dies because they can't control their aggro and they get eaten alive faster then your fastest heal can fly, it is your fault. No matter what, whomever dies, it is your fault. As long as you have a little thick skin it really is not that much of a problem again. Just say, sorry you died, was out of range or I really tied to save you but you are squishy. 95% of the time, unless it really was your fault, like not trowing any heals what so ever, no one minds a death here and there. Nice query time and not a ton of stress as long as you have competent people around you makes gearing up a healer somewhat easy. But at starting stages I would still only go with people I know as I am getting into the grove of group healing.
Tank - DPS is not high enough, its the tanks fault, healer is letting people die, its the tanks fault, adds come out of nowhere, its the tanks fault, all the DPS being aggro monkeys, its the tanks fault. No matter what happens its the tanks fault. The weather sucks today and it is raining, must be the tanks fault. If DPS has low DPS but is trying, its okay they are trying their best. If a healer is having trouble keeping people alive, its okay they are trying really hard and just need some better gear. If the tank has any issues, the tank sucks. At least in my limited experience tanking at 80 with my Druid I can tell you I will only tank for people I know. I will never tank for PuGs, ever. No random heroics for me unless I can get guild group up that includes at least a pocket healer and 1 DPS. The theory there is that I will tell the healer if the other DPS are jerks let them die and me, you and the guild DPS can do the whole dungeon alone. (I think I am going to make a grumpy tanking post to get more into this one)
So when the time comes, as it will soon for a few of my characters, I will get some gear for my Shaman, my mage and my rogue (oh god how I hate being a rogue) but I am not sure if I will work on my warrior at all when it comes to gearing up. My Pally is still up in the air as I do not know what the second spec will be yet. I am leveling Retribution.
In the end, I doubt that I will ever have a great deal to compare my Druid's tanking with and my Priest's healing with. So just like my Hunter is my favorite and my main because it was my first I think the Druid will be my main tank and the Priest my main healer because they where my first.
One thing about firsts however, once you have that first one done, the rest are a cake walk really. After leveling my hunter all the way, taking a full month of time played I now level characters in no time at all really. I now have no issues going into dungeons that originally I stayed away from on my Hunter. I have experience with one character which makes doing it on others 100 times easier. So perhaps if I ever do try another tank or another healer I might be better with them because things are always easier the second time around.
I wonder if I am the only one that ever considered having 3 mains. One for each role. The way I look at it, they do not really interfere with each other as I would never mix and match them. Well... maybe I can, my druid is a bear and a tree. Oh well. There goes that idea.