well.. I play an avatar mage prime, and a th/ma who's close to tri40.. and really, they are both fine solo char, just for very different areas.
As Shadis mentioned - if I get lucky with stabs, my 2x40 th/ma can solo almost as much xp per run as my avatar mage, simply because it's easier to splork a 1.5mil mob for a total cost of 20mvs and some poison than it is to blast a 1.5mil nostab mob, use 50-75 mana on winds, and another 80 to remirror - granted, there is a difference of almost 200 mana between them (in solo gear - obviously much higher when the mage is in regen gear), but that gets used up fast. My mage runs -10 ac, so he is much more suited to thick mob - stab, dam, blind, and blasting out, he can kill much bigger mobs than my thief, who has not-so-good ac, due to his much higher damage.
As to your point about 18 dex - anyone who runs anything without 18 dex, either with eq or nat, is insane

and 18/100 str is even more important for thieves than any other classo - stabbing without that is just kind of silly, thieves live and die by their stab, so the bigger the better, except perhaps on valk, where you can not get as high damage, and have no doublestab.
What class you play to solo depends greatly on the areas you want to run - no char is going to be perfectly suited to everything, and really, there is a good enough selection of areas in the mud that I think most classes can find stuff to kill at most levels - yes, some classes do level much faster much earlier on; there is absolutly no comparison between my ma/wa when he was 2x40, and my th/ma now, in terms of total xp or coins they can make in a run - but my thief has been running pretty much the same stuff since around 1x40, and will probably keep running them until he makes avatar, whereas with my mage whole new worlds opened up at 3x40 in terms of interesting things to do.
Never played any of the other classes even to 40 prime, so I'll keep my mouth shut about them
would also like to point out that this is a game, played (theoretically at least) just for fun - stats, numbers, total xp, total coins, yadayada aside, I think thiefs are about the most fun class to play - sure you die alot, and sure your runs end rather abruptly if you doublewhiff, but very few things in Sloth give me more joy than a damned good run through Infernite mines or something with my thief
