Aside from the joy of playing Injustice as a comics fan, I really really enjoyed that I could find something fun about playing each character. My top 2 are definitely Green Arrow and Batgirl, but it starts to get harder to choose from there. I definitely would also put Solomon Grundy and Batman up there too, I totally get why you have them in your top roster.
I never owned Injustice 2 and unfortunately didn't get to play enough of it to choose, let alone get to try all the awesome new characters they added. I'm sure a day will come at some point where I finally get a real upgraded gaming experience and can then get the sequel for myself!
Bruce Coville is such an incredibly fun read for young Sci-Fi fans. I flipped through some of the Aliens Ate My Homework series recently now that I'm older and it's still a great time. Coville really did well at writing in a way that makes it understandable and enjoyable for kids without dumbing down ideas that would help spark the imagination and garner understanding for more advanced works.
I should flip back through the My Teacher is an Alien series too at some point. I'm pretty sure I at least still have a copy of My Teacher Flunked the Planet here somewhere.