It sounds to me that you are looking for char that's a bigger challenge. Now which char you choose will depend allot on how you play the game. Do you like to be in the middle of the battle or stand on the back lines and do damage from far. What I like to do is I try all char so that I know what their weaknesses and strengths are. So when you play against them you know how to take them down. And you also learn which types of char's you like.
Assassin is very nice, but you have to do certain spells in a certain order. You do a Lead Attack, Off-Hand and Dual Attack. If you are interrupted your screwed, but if you like the "surprise" people this is the char for you. Assassin is also better for PvP than PvE, because you do spikes which are focussed on one person at a time.
I have never played Rit but what I read about them, they are very powerful and a bit of a underdog. They can heal and do massive damage. They are a bit complicated to play, but it sounds like it's all about good timing. They also do very good in PvP.
My personal fav is Elementalist. You can use fire magic and nuke the hell out of people from far and don't get a "scratch"!! Or you can play Earth Magic and have a lot of armour and take allot of damage, or you can slow people down with Water Magic. And I also like Mesmers, because you can give people allot of armour ignoring damage (well, you played Warrior so you know that Mesmers are your Kryptonite). Mesmer is a very challenging char to play, because you can't do any physical damage except with your wand or if you use the spell Illusionary Weapon.
If you want to read more on diffirent proffessions you can go look here.
http://gw.gamewikis.org/wiki/Profession