We started at 6mos with the Avent sippy but she didn't quite get that she had to tip back her head to drink from it. We switched to the Gerber straw sippy-hardly ever spills, solid wide base, two handles and the straw top flips over to close it. Easy to wash. She picked up on the straw really quick which I like bc if we are ever out and forgot her sippy, she'd just use a straw. The Avent ones are a pain to wash cuz you have to wash all the parts ie, seal, plug, rim etc. I also heard that normal sippys can sometimes impede speech development as teh formation of the tongue is different than that of using a straw.
M now uses all types. She's got straw, normal, Nuby (they hardly leak and there are no extra valves to wash), and older kids sport sippys which aren't really sippy but they have to learn how to suck from teh rim.
No prob's with any of them. It will likely depend on how your lo does with what you get...