I don't play much from CD, and gapless has not been a priority.
Aqualung and Audacious are great in that though ...
Try deadbeef too - looks like foobar2000
Gapless is not just about playing from CD: it is about playing any music (eg live concerts or classical recordings) where there is no silence in between tracks. The tracks can be files on your PC.
I think I looked at DeadBeef. There was a time when I downloaded a heap of different players.
Oh, I have another requirement, what with having a Firewire interface and Ubuntu (bad choice in some ways) and that is the ability to output to Jack. If the player is "jack-aware" that helps a lot. One can go player->ALSA->Jack, but, whether it impacts the sound or not, it just bugs me in principle to have unnecessary stages in the processing.