128 gb is a huge amount of memory and you are unlikely to need that much, but be aware that a memory card is usually storage memory (for books, movies, music, etc.) and not all apps can go on a storage card. The games you are listing don't really require much memory so you might be OK with a Kindle.
If I were buying a tablet given your needs and the current state of the art, I'd look for a minimum of 16 gb (32 gb is better) and a quad-core processor. Also, I'd look for a minimum of 1280x800 screen resolution.
To be honest, I have an original Kindle Fire HD, and I can't really recommend Kindles because to me they are really just an advertising platform for Amazon products and services.