So I checked out Toyshop Trouble as well as Oystron and Blinky goes up.
Oystron looked great and original, but I could not figure out what you're supposed to do from the video and the descriptions and it seemed a little too frantic/multitasking for my taste.
Blinky Goes Up looked pretty amazing. Simple level design with great fluid animation. Reminds me of Mega-Man for some reason. However, it's not yet available, so there goes that one.
Medieval Mayhem seems fun and really well done, but it's essentially a nicer version of Warlords, which I already have. I might get this someday, but I don't think it's a good choice for my first homebrew purchase.
Toyshop Trouble seems great, addictive, and fun, not to mention, original. For an action/puzzle concept it's pretty new, especially for the 2600. Reviews saying the difficulty curve is just right adds to my interest in this game as well as the fact that several coders collaborated on it. It also seems like it does a lot while not trying to bite off more than the 2600 can chew and making me wish it was on a more capable platform. Because of these reasons and the majority in the recommendations, I decided to purchase this cartridge from AtariAge.
However, I believe this topic may be useful for other people so keep replying with your favorite homebrew!