Since I love to many I'll just post a few, mostly from all the Final Fantasy VII games

Cosmo Canyon

Ahead on our way

Zanarkan

and of course

^Anytime this song get's played all hell breaks loose

My all time favorite:

This one is epic:

And then some more recent composition:

The Brawl main theme is his best work.

Aerith's Theme... Just listen to the crowd cheer when it properly starts and they realise what it is

And...

Terra's Theme

I could go on for hours though.

One of the best pieces in the series ever!

Waltz for the Moon FF8

These are close
Terra's Theme FF6
Liberi Fatali FF8
For Those Who Fight (I think that's what it's called) FF7
Zanarkand FF10

FF8 and 7 soundtracks are my favorite... but I don't enjoy one winged angel.

His battle themes are awesome too:

This is a remix done for FF XII, but the samplings are just better than in FF V:

And yeah, I could go on and on... ^^,

I'll take this chance to post some of his most underrated songs:-

Chrono Trigger - Sealed Door

Final Fantasy I - Matoya's Cave

Final Fantasy V - The Decisive Battle

Final Fantasy V - Fate in Haze

Final Fantasy VI - Phantom Forest

Lost Odyssey - Parting Forever

While I personally think Yasunori Mitsuda's music is far better then anything Uematsu ever produced, I do still enjoy a lot of his work. I agree with the most of the songs above, I'd put my vote in for Terra's Theme as well, followed by Melodies of Life.

My personal favorite version of FF VI's Mystic Forest theme (Fab_GS, yours is a very bad remix of that theme, it sounds like crap O_o):

Oh, and I almost forgot, FF IX's map theme, Crossing those Hills,  is so... soothing: