User blog comment:Rutgerman95/Doom 64 console port: TC or EX/@comment-295-20110216024441

The EX engine is a lot closer to the original game, so pick that if faithfulness to the original game is your main concern. It used a WAD that is dumped straight out of the ROM, so the levels are exact copies from the N64 game. The engine is the only difference, and even there Kaiser is aiming to create an experience as close to the original as possible.

The TC takes more liberties and features differing levels here and there. Plus it has several totally new levels not seen in the original game, which can of course be a plus, depending on what you are looking for. And of course the engine is totally different, as the TC is built on Doomsday.