My favorite is Liquitex BASICS. You can get them at Hobby Lobby for just a few bucks, and an even better deal when they run art supplies on sale (which is usually when I wait to stock up)!
I keep all my paint in this great little wooden suitcase I found in college that I keep little tidbits of memories and inspiration inside of as well. It's such a happy feeling to open it all up and see all of my colorful bottles just waiting to be used and fond memories of art school and friends posted inside. It's kind of like a time capsule. The paints in this suitcase have been part of many works throughout their little lives!
In fact, this suitcase makes traveling with art supplies super easy. It took a two week adventure to Italy with me once :)
Storing your paints in a protective and sturdy container is a MUST! Even though one of the clasps of this box is broken I can't find it in me to get rid of it after all we've been through and seen together :)