I've had great success with a trapsin. Amazing crowd control with Cloak of Shadows and Mindblast, traps that can allow her to shoot around corners, and the best weapons can be shopped for. My best, fastest, and safest Baal runner.
I like the trap-sin and with moderate gear I enjoy running an Orb/Fire Wall/Lightning Sorc who I like to call "Broad Spectrum" the Anti-biotic of Hell. I won't kill anything immediately, but I will kill everything eventually.
TBH tho if we are talking about strongest or easiest I really cannot see how anyone can go anywhere except the Pally. He can do Baal easily, He can do Annihilus runs, and everything else basically......He is the one stop shop for being OP and ridiculously easy to run all wrapped into one.
My first character in D1 was a Sorcerer, in D2 it was a Soceress, and in D3 of course it was a Wizard. The fantasy part of using the elements as weapons and contorting space and time are my favorites as well. The buffs to Frozen Orb in D3 had me considering a little run in the next season, but any consideration fades for me rather quickly.
I cannot decide between paladin, sorceress, amazon and barbarian. Amazons (those with bows) are most fun, sorceresses are most effictive (so I choose her when starting from scratch), paladins and barbarians have many build options.
There is no answer to this really, if there was a generally "best" class the game wouldn't be balanced. Question is how do you measure "power" of a class or build. Best times in Baal runs? Diablo, Meph runs? Fastest levelling? Fastest to farm runes? Best MF char? Best Pit/AT runner? Or just pure killing power, as in fastest to kill 10000 monsters? In that case, nothing comes even close to Infinity Javazon. But she won't get much out of it since she can't MF as well as others. For MF (Pits/AT/Pindle) - nothing comes even close to a Barb in terms of MF ability, but he e.g. a Zerker already gets into trouble vs. any average /p8 elite pack. Sorc is clearly best to farm HRs (before Enigma) and probably will level the fastest as well, and is good in other categories but not the best at anything else, and so on... Then when considering Enigma, it all gets mixed up again...
In short, best char depends really on what you want to do. That's the cool thing about D2 as opposed to D3 and other games - the best chars for a specific task are really specialized and optimized for that task, which means they are (mostly) terrible at others, and that's exactly how it should be.
I remember the first class I beat hell on was the paladan! I remember switching from Zealot to hammerdin late NightMare because I saved the skill/stat reset and then walking through Hell like a piece of cake.......wait a sec. who would walk through cake
Then I ran a singer barbarian and then I have played that ever since.
If we go into D3. I used to be a sorceress main, but I would only be able to play at torment at most. When I maxed a witch doctor. I easily got to torment 4....now I'm running torment 8-11...
so I'm a witch doctor main....