E.I.
The best tip I learned, is buy all sippy cups of the same brand, once you find one you like, and buy all the same color. This way you don't have to keep track of different lids and matching colors and such.
I bought every sippy cup in the market and the only one my son took, was a cheap cup from HEB. Dont know the brand, but they have a whole bunch and they are only $1. I buy them in all yellow, and it's only two pieces, the lid and the cup. No valves to keep track of etc.
Also, they don't leak at first, after 2 months they do start to drip a little if laying flat, this is mainly because my son bites them and tugs on them. But at $1 a pop, I just replace them.
Hope this helps.