Barenaked Ladies' Rock Spectacle hands down. All the songs from that set sound so much better than their original album recordings and just more enjoyable in general. I suppose their All New Revue - Live at the Glenn Gould Studio album is worth mentioning as well, as the songs on it are as good/better than the original recordings, but it's not as good as Rock Spectacle since it's not anywhere near as energetic. Besides that, I'm much more partial to the era of songs on Rock Spectacle than those on All New, which is exclusively from their Are Me/Are Men albums.
Also, I thought H.A.A.R.P. was a pretty great album. It had a lot of my favorite Muse songs performed amazingly well, so I had no complaints, other than probably having preferred a few songs be included over others, but oh well.