I just got the Nutribullet (not the old Magic Bullet) and it works great for protein shakes/ice/frozen fruit/nuts/veggies. Went with that because its a little smaller than the Ninja and a little cheaper ($80 at bed & bath with 20% coupon). Great for one, but the Ninja has more attachments and options I think. As someone with counterspace issues, the Nutribullet has been great!
I got magic bullet, nutri bullet and ninja. nutri bullet is great it is much better and improved from magic bullet and it is smaller than ninja. It does much more than just shakes and I love it. Ninja is definitely a good investment if you planning on using it for other stuff. ( i hardly use mine, but i like having it My advice; buy the nutri bullet first and see if it's good enough for you (i use mine everyday and it's super fast to clean; i guarantee u, you'll love it) if not satisfied, return it and buy the ninja.