Again i'm more of a GM than player, but if I were to roll up a class that I know and love it would be the Rogue/Thief. The earlier editions of D&D were great for a Thief, but its really the later editions that I like better, Martial characters have been brought up to speed combat wise so i've always felt like I could contribute more inside combat than before. (not that it hasn't always been fun mechanically, it has)
Im not always about acrobatics, although thats cool - for me its about the knowledge of how to detect and disarm traps, knowing the best way to get in and out - and crucially being able to do it silently.
I especially like the thief class because of the ambiguity it inherently offers, i've always found character with questionable or undetermined moral compasses much more appealing to play. I tend to play the good guys, albeit ones who keep everyone guessing that fact. Maybe thats the GM in. Keep 'em guessing.