I think it depends on what you want to do. Color images? Stamp sentiments only? Edge papers?
Are you using clear or rubber stamps?
I prefer memento for pretty much any time I stamp, unless I need it to be on weird material like acrylic. Then it's staz-on. You can get a set of something like 12 different colors of memento in tiny ink pads at Hobby Lobby. With a coupon, you can get the set for around $12-$15, I think.
If I'm edging papers, I like cats eye chalk inks or distress inkpads.