There weren't too many potential builds because of only 4 classes and 3 specs but not all of them being super viable, but I did like how clearly they were defined and unique from each other.
My favorite in the end before I was done with the game was Fire mage. I had a bunch of passives stacked up to do a lot of damage over time mixed in with burst with the delayed explosion skill, and it was super fun to play with rain of fire slowing down, grouping shit, then exploding all of them. The funny thing is I made a youtube video of the build back then to show the build in their forums, and I kept getting youtube messages for years after about people asking about it until I deactivated youtube messages. It was funny to think people like 5+years later were still playing TL2, looking at builds and finding my old ass video.