I still love Build engine a lot, it's one of the first 2.5D engines and it had lots of possibilities, especially for its time. My fav games on that engine are: Blood, NAM, Powerslave and Plunder & Pillage kek. Also Jedi engine is very similar to Build. It was eventually made for Star Wars: Dark Forces. But i especially like Outlaws on that engine. It's still my favorite western game.
And what engines do you like?