iTunes will definitely handle MP3 and WAV (if you can persuade Bandcamp to give you WAV, which I couldn't last time I tried). WAV is basically a copy of what's on a CD, plus a header, so is "CD quality" but big. FLAC is a compressed version of that (as free/open format, but a number of things don't support it) but still lossless so the same quality (about half the size of WAVs). The MP3s which Bandcamp provide are at 320 kbps which is as good as you get with MP3, there is some 'loss' in compression but they are smaller (about a quarter of the size of WAV); I can't usually hear the difference between 320kbps MP3 and WAV unless the source audio is really strange.

Ogg/Vorbis is another free format, but is about as popularly-supported as FLAC, it's another lossy compression about the same as MP3.

If you aren't constrained by low bandwidth I'd go for WAV (remembering that a full CD of 'WAV' type music is still under a gigabyte so fairly small by modern standards). But if you are used to MP3 quality anyway then go for that.