I have to go with the majority here and say Beaucoup Fish, although for a different reason. Everyone else says it's their most accessible album. I say it's basically their best.
If you don't think Cups is a wondrous work of subtle progression, then I don't even want to speak to you. Most people, on listening to BF for the first time, would just skip it. Don't. It's brilliant, it's amazing. If UW had truly wanted to make it their most accessible album, they would have started with Push Upstairs, but they didn't. They started with a sublime groove that draws you in with its hypnotic vocals, and then completely throws you at the end.
Bruce Lee is incredible. In fact, right now, go
listen to the live version, because in its truncated studio form you're in serious danger of missing the actual story that the woman is telling. It gives me goosebumps every time.
Push Downstairs is pretty awful, but apart from that it's brilliant track after brilliant track.