For soloing pve, combat is your best bet while leveling (plenty of time to play with the other specs later, plus it gives you a lot of freedom to try different weapons and see what best fits your playstyle). Agi is the magic rogue stat that does almost everything we like, and stam is what keeps you alive. Strength is not a "bad" stat per se but we gain AP from agi as well as str, and we get so many other nice things from agi (dodge, crit, armor) that str can be neglected. (I.e., most of your best leveling gear will be "of the monkey" type things.) AP and crit are your lovely things to look at while leveling, and dodge is your best line of defense soloing.