I don't know who I should save on Virmire anymore

Barbie-doll makeover cracks aside... You can get some different insights into Ashley if you do some very specific things in ME3.  For example, if you recruit Tali before doing the Turian Bomb mission and then take the two of them on the Turian Bomb mission... then go down to talk with Tali afterwards, you overhear very different dialogue from Ashley.  The romance scene during Priority: Earth (i.e. talking in London) does yield an Ashley who is much "softer" and perhaps more vulnerable than she is otherwise.  If you romanced Ashley in ME1 and Miranda in ME2 and then continue to romance Miranda in ME3 (and then just withhold the Alliance data from her such that she dies while being romanced by Shepard), Ashley does come across as being somewhat sympathetic regarding Shepard's loss.

I admit that it's still not great and Bioware could have (and should have) done a lot more to flesh out Ashley's character in ME3.

I guess it's a better overall and she considers Tali a little sister (she only mentions that though if Tali dies AFAIK), but generally she still comes across like she didn't that progress much. I also was kinda disappointed by all her scenes. For example you get a nice talk with Kaidan once he joins the Normandy, Ash doesn't get any scene here. After Gellix, Kaidan has a great scene about Cerberus, in which you can see that he's willing to give things a different perspective. Kaidan interacts with James and Engineer Adams, while Ash only interacts with Vega off-screen and you only see the aftermath of her being a drunken mess on the floor. I think she gets a scene with Tali though over the comm (but then Kaidan has at least one with Liara as well). Not sure if that's the scene UpUpAway mentioned, but I guess so.
Ash is also more hateful of the geth in general, while Kaidan appreciates the quarian and geth support if you broker peace. He comes across as more open-minded than Ash to me.
I'm not sure if this is helping you, maybe you should wait for someone who is a big Ash fan (I'm not, but I don't hate her ). But for me, Kaidan is far superior than her in both ME1 and 3. Even in ME2 or should both be killed at the Citadel coup, Kaidan comes across slightly less aggressive, but maybe that's just my imagination and biased opinion

For me it depends on the Shepard I bring through, if I'm planning romance with one of them, it's a non decision.

Currently replaying the trilogy now in anticipation for Andromeda, Kaidan is going to be the one dying on Virmire, though, Ashley will join him shortly as she will be gunned down on the citadel.

Ashley has 2 scenes on the Citadel One involving her sister and the other just talking with Shepard

Kaidan has one. In the same spot where Shepard can talk with Ashley

Do you get the second convo in a non-romance?

The second Ashley meet-up on the Citadel, after the one about her sister. I don't normally keep her alive unless she's my ME1 romance, so I don't recall having the second meet up with a femShep or non-romance male Shep.

Even if she isn't romanced, she still has the second meetup.

Yeah, Ash has the scene with her sister on the Citadel and the talk about her father in the same spot where Kaidan's dinner scene is.
Kaidan has a scene after first coming to the Normandy (where he stares out at space) and one after the Ex-Cerberus scientists. Ash additionally has the drunk scene, so they're equal in scenes, but whether the content is equally great depends on one's own taste. Ash's dialogues are family-related and well, being drunk. Kaidan talks about different things and I personally think this variety is much better.
Pretty sure though that Kaidan has more interaction with the crew. He spends time with Adams, plays poker with Vega and talks to people on the comm. I know of Liara for sure. Then there's a scene with Kaidan talking to either Garrus or James (if Garrus is dead) on the comm. This happens after Tuchanka: Bomb, so the same spot as Tali and Ash (which means the Turian Platoon/Bomb mission has to be delayed). He also has a tiny conversation with Shepard after the geth server mission (Ash will have the drunk scene here).