Oh I agonized of this little task for the past couple of weeks. I grabbed about 100 album covers that I liked, put them into a directory all together and just sat and ran through them with an image viewer, over and over and over again, dropping off a couple every time. Then I got to the mid 20's and it REALLY got hard.
Seriously, if I had to do this all over again, without being able to look at the ones I just posted, it might come up different. TEN was so hard for me.
BTW, I was a bit surprised that you didn't have any Maiden on yours. I think I had 5 or 6 Judas Priest covers at first and agonized over dropping a couple of them.