I happened to have used all three, Palemoon wins out by far, It is optimized to be used on modern (SSE2 and up) CPU's, comes in 32-bit and 64-bit flavors, I use the 64-bit admittedly because i find 32-bit needs to die as far as browsing goes, I know 64-bit doesn't really provide anything additional. But it's time to move forward (can't even get a 32-bit windows 8 i don't think)
i don't use to many addons, HTTPS anywhere, Greasemonkey (Youtube HD script

), Adblock, and omnibar. So no idea how compatibility is, But I'm fairly certain that it'll be fine.