Thief, mesmer, or necromancer
I love my mesmer for PVP but absolutely hate PvEing with him as wonky phantom/clone mechanics makes it difficult to get anything easily done. Generally, I wouldn’t recommend a mesmer for WvW either as your phantoms/clones become useless in any engagements larger than 3v3 since they die too easily to AoE.
Can’t comment on theifs and necros but they both seem to do pretty well in PvE.
Lee Oren – Ranger
Eve Oren – Revenant
I play mostly open world pve, solo or with my sister. Love my mesmers, have no problem with them. You will need to get traits for them otherwise they are not much fun. My least favorite to play are thief and necro, but that’s just my preferences. You should discover your own by trying them all.
For solo pve I’d say thief.
They can solo most non unshakable enemies with the help of off hand pistols black powder while doing ok damage with sword or dagger main hand.
They also have access to a lot of stealth techniques for getting away or passing unnoticed.
Thief is good for both PvE and WvW roaming. My thief is my main and I find it very versatile in both situations.
Necro can do well in PvE and it’s useful in WvW though I can’t personally speak to the particular strategies of roaming with a necro as opposed to running in a big commander group. It’s fun to run necros regardless of what you’re doing.
Mesmer has a bunch of utility in WvW and there are many videos on youtube of mesmers who really know what they are doing dominating enemy players while roaming.
For mesmer in PvE, it can be a bit wonky to level up, but once you get there you have a few options once you can get some traits unlocked.
http://metabattle.com/wiki/Build:Mesmer_-_S/S_/F_/P
I recently came across the above build and I run a modified version of it in general PvE even though it’s marked for dungeon use. It’s the quickest killing PvE mesmer build I’ve come across and I’ve started PvEing with my mesmer a lot more after discovering this. Before then my mesmer was a big drag in PvE battles.
If you have just one character slot you’re looking to use up, make each class one at a time and spend a little time playing around in Heart of the Mists and sPvP matches to get a feel for the classes. That’d be a great place to start since you have everything unlocked in sPvP.
(edited by Mo Mo.1947)
For me personally? Mesmer is the most fun, even without traits it is smooth levelling. Necro can survive just about anything. Theif I just don’t get, that is I can play it but not at the level required to solo champs which I can do on the others.