To die, Ashley or Kaiden? I sent Ashley to the nuke site for some fucking reason and know I dont know who to save! 
 
I am a soldier if that helps with anything but I might change to a Vanguard in Mass Effect 2.

You can save either of them regardless of whether they are at the nuke site or the AA towers. If you save the person at the AA towers the teammate at the nuke site will die detonating the nuke.
 
Neither of them become squadmates in ME2 so just pick who you like more.

"You can save either of them regardless of whether they are at the nuke site or the AA towers. If you save the person at the AA towers the teammate at the nuke site will die detonating the nuke.  Neither of them become squadmates in ME2 so just pick who you like more. "

  Cya Ashley, you whinning little bitch! "

My 3rd play-through was as an Adept and Ashley became a strong asset to my team.  I'd Singularity enemies and she'd one-shot them with the sniper rifle while they were in the sky.  Also, as far as her personality goes...
 

The first time I played, I thought about this for like, 5 minutes. Eventually settled on saving Ashley because she had been in my party the whole time.
 
Every single re-play though, I save Kaidan. I just don't really like her that much.

I always thought that Kaiden was a really boring character.

Saved Ashley so I could sex her. 
 
It was worth it.

Kaiden is boring, but Ashley can be really annoying if you don't care about her already or like that personality type.  Kaiden is cool like in a "dumb young cop" way for me.  I don't know what that really means but yeah.