Good variety of stuff here. Lots of good studies, stuff from ref, realistic and not. You did get a little scribbly on a couple of them, and some of them seem to have gotten a little distorted. To help with the destortion I think you should just keep doing your perspective studies on the side, and also try to think about how perspective effects your subject when your drawing other stuff.
[Always remember that if a topic seems uninteresting, then it's just because you are picturing a solution that lacks vigor.] - William b. Hand