So I've finally collected a decent amount of 3* allies and I was looking at some of the 2 and 1 * allies I've been holding on to and wondering if it is worth it. Some of them have really neat abilities but the 4* and 5* characters have a lot of cool passive abilities and seem better.
I have seen a couple of 3* allies upped to 5* on some of my Troopers and they kick major butt (especially the level 80 undead allied soldier) so I can see the value in upgrading some of them.
So my question is, are there any 1* or 2* worth keeping that could be worth leveling to 4 or 5 * in the long run, or is it better to just sell them to free up slots?