the main ones would be :
Vitality health drain kinda build
(Personally didnt like it because single target damage is ass until lv 40+)
Ultraman-styled beam action
(I tried it until level 50-ish, the mana management kinda pain in the ass until you get juicy mana regen gear, and overleveling Albrecht’s Aether Ray might ruin your day due to insane mana consumption)
America Simulator 2020
(I really like it, you just throw molotov and most of the things will melts)
2020 Simulator 2020
(Word of Pain is my favorite skill so far, at least for leveling until level 60-ish. the AoE is really REALLY huge)
I would recommend you checking Beginner Build Compendium for further reading. But don’t worry about it and just try all single-class build at least until level 30. Don’t be afraid to respec your skills and try all of each class skill to find the one you would love the feel of it.