It was six years ago, but I have to say I had the same bad, leaky experience with Avent! I don't know how they compare in price now, but back then they weren't cheap!
I had luck with the old fashioned Playtex (with drop in liners). When you're at home it's hard to appreciate the liners, but when you're out it's nice to be able to throw out the liner and not have to put a dirty bottle back in your diaper bag. I don't mean to be gross or offend anyone, but the easy drop in liners do look like a used condom when you throw them away. I'm sorry, but it took us a while to get over being weired out by that.