I'm quite impressed with the Bob Martin ones, I had to buy a couple of new ones from my local supermarket, it was a bit of a rush job, and I always like to have a spare. So far they've been great for the pigigs, no leaks and they have a lovely large spout with no ball bearing bit, and they find them really easy to drink from.
Wouldn't recommend them for bunnies though, my (now deceased) beautiful grey bunny, managed to dismantle one in 2 days, I am still baffled as to how and where the missing piece went, but it was in no way was involved in said bunnies demise, that was just plain old age.