I recently did a similar dungeon leveling path on
the Al'Kabor project, which is a year-old, cross-platform emu project that'll eventually cap at the Planes of Power. Up to three boxes are allowed, so I played an enchanter, cleric, and mage. I should've made some videos -- yours are fun, Tecmo!
Here's my thread about it. It's pretty similar to this one.
I really enjoyed Najena, particularly the north wing of the basement, which was great exp through the high 20s. I wandered all over sola in the 30s; I especially enjoyed the bar and King/Gimblox camps. Solusek goblins (mid-30s rogues) absolutely annihilate the lower-level goblins. I spent the 40s in Kaesora, almost exclusively at the church camp (Xalgoz and friends). That got pretty boring by 46, but the exp was so fast that I stuck around until 49 anyway. Looking back, I wish I would've spent more time exploring lguk, solb, and the Hole. I've been hanging out in Sebilis since 50 (I'm 57 now), variously camping the bugs, disco1, disco2, jail, and crypt. I'll probably hit up Chardok (which is a playable zone on TAKP) and Howling Stones soon.
I love ToFS. I would've done a lot of levels there, but TAKP is still in Kunark. Oh well, maybe I'll level up another trio doing icy dungeon dives after Velious drops this fall.