I own and use a Fostex VF160 (now VF160EX), a truly great machine that can be had for $799. Incredible. Very solid and stable. CD burns are flawless. 16bit, 2 XLR inputs, effects are OK if not overused. I do all recording, mixing, editing, burning on the Fostex.
I think there are many great machines, and if you can't make a great recording on any of the ones mentioned, it will be your fault. I say that smiling, in the sense that the technology out there is wonderful.
The Korg D1600 mkII is another fine machine, and I think that I'd go there before either the TASCAM or the Boss. One reason is that it will also do 24bit recording (though not as many tracks at once as the TASCAM). But also because it's got a reputation for being easy to use, Korg support is excellent, AND this machine has been out a long while and doesn't seem to have any systemic glitches left in it.
My understanding is that the TASCAM 2488 has had some teething issues, and my sense is that people don't love TASCAM support... tascamforums.com is an excellent forum that seems to take the place of TASCAM in terms of tech support.
Boss machines often record with data compression. You'd want to make sure that you could record with no data compression. Boss has a reputation for great effects -- which you could really take advantage of.
But really, all of these recorders are very capable of faithfully giving back what you put in.
You may want to take the time to download the manual of something you're thinking of getting. I've found Korg manuals are very clear, others not as much. Looking at the manual gives you a good sense of what the machine will be like.