From Slippery to These Days all of the first tracks seem like great openers. They may not (or may to some people) be the best songs of the album, but they all served the purpose of opening their respective albums. It's a shame that it ended with 2000s and since Crush there's a trend to most often have a lead single kick of the album, which makes for very little (or none in Because We Can's case) build-up to kick things off. Undivided is the exception and, while a great song, does seem out of place as an opener. I much prefer when lead singles are in 2-4 slots.

But if I had to pick one, I'd also go with I Believe, but once again, from the "big four" (and even Billy from Blaze) they're all great.