A lot of it is going to come down to trial and error. Not only do I hate erasable pens, but I have a serious dislike for bics, papermate, etc. What I currently use (most of the time) is Uniball Vision Micro, although there are a couple models of Pilot that I don't mind too much.
The best thing to do (although it can get pricey) is buy one each of several different types of pens - gel, ballpoint, etc. Get different colors too - I would swear that the blue ink (for example) of one of the Pilot pens I use dries more slowly than the black in the same model, because the blue smears and the black doesn't.
Once you find one that she likes, buy as many as you can. As is the case with so many other things, as soon as you find something you like, they discontinue it.