Haaaa so much FFVI love, that's my Neogaf as i like it!
As for my general opinion, FFVI is the best of course, but everyone is truly great, even FFVIII (but as someone said, the sound library of the game killed it somewhat).
After that there was some bad things but Lost Odyssey is worthy of the best old school tracks.
From FFVI not really known pieces, i'd say The day after as it was already said, or Searching for friends (well known already) which is the perfect song! And i'm a huge mega fan of the recently arranged
Dark World
This is one of the only good re-arrangement of FFVI ost for me, as every other one seems cheesy and two light hearted. FFVI is so fucking dark, slow and sad... This orchestrated song single handedly shows how out of this world FFVI is in term of maturity and tone, compared to every fucking videogame ever.
I also love the Grand Finale orchestration from Shiroh Sagisu (composer of Evangelion or Bleach) and i think its baroque and totally anachronistic tone is perfect for what is FFVI in my heart, but sadly Uematsu doesn't think so! It's actually really confusing to think my eternal love for the music of FFVI is not even in line with what Uematsu think of is own work..
Also as wonderful non FFVI bonus track :
Silence and motion