In many of these cases, I like the original and the alternate versions "only" equally, but I'll list them anyway.
Remixes:
- kanariya "system F remix"
- P.S II "Dub's Kingship Remix"
- A Song for ×× "030213 Session #2"
- YOU "northern breeze"
- HANABI ~episode II~ "HAL's MIX 2003"
- It was "Island mix"
- Depend on you -10th anniversary version-
- blossom (Clockwork yellow remix)
- Dearest (Razor N' Guido Club mix)
- For My Dear... (HOUSE NATION remix)
- snowy kiss (Shohei Matsumoto remix)
Acoustic & Orchestra versions:
- Who... (from ayu-mi-x II & 4)
- Fly high (from ayu-mi-x II & 4)
- Key (from ayu-mi-x III)
- Duty (from ayu-mi-x III)
- Far away (from ayu-mi-x III) - the original arrangement has always irritated me a little, so this version is great
- ever free (Inst Melo Version from ayu-mi-x III)
- GAME (Orchestra Version from MY STORY Classical)
- HONEY (Orchestra Version from MY STORY Classical)
- kanariya (from ayu-mi-x 7)
- Trust (from ayu-mi-x 7)
- forgiveness (from ayu-mi-x 7)
- blossom (Orchestra version from crossroad)
- Song 4 u (Orchestra version from LOVE)
Live versions (spoiler: I really like PCDL and PoM lol):
- A Song for xx (DOME TOUR 2001)
- End of the world (PREMIUM COUNTDOWN LIVE)
- Heartplace (PREMIUM COUNTDOWN LIVE)
- And then... (PREMIUM COUNTDOWN LIVE)
- forgiveness (POWER of MUSIC)
- progress (POWER of MUSIC)
- A Song for xx (POWER of MUSIC) - LOVE the brass in this version
- BLUE BIRD (POWER of MUSIC)
- WE WISH (CDL 2013-2014)
Honorable mentions (not loving them quite as much as the originals, but it's really close):
- monochrome (POWER of MUSIC)
- HEAVEN (Piano Version)
- HEAVEN x DAISHI DANCE
- MOON (Orchestra Version)
- WHATEVER (from ayu-mi-x 7 -version Acoustic Orchestra-)