Since we don't actually get winter here, I stocked up on rain gear when Riding Warehouse was having the sales around the holidays. The two main things I got were a Kerrits rain jacket and rain boots. I was waiting until I got caught in a downpour so they could be well tested. Unfortunately, I waited so long that the jacket has been replaced with a similar style and the boots are steeply discounted so I am guessing they are going to be disappearing soon too.
The jacket is the Kerrits Outsider Waterproof jacket. It wasn't the one I really wanted, because I wanted a longer coat that would cover more of the saddle. But I couldn't find exactly what I wanted and this one was on sale so I bought it. I absolutely love it. It is waterproof but still breathable so you don't automatically feel like dying when you wear it. Also, it's light enough that I can wear it in the rain here (probably won't be doing that in the summer) because it doesn't cool off when it rains. I have room to layer under it when necessary. Finally, it passed the downpour rain test like a champ.
The boots are RockFish Wellies. While I like them because they are holding up well, I don't like that they are unlined rubber. They get really hot when it is warm and really cold when it gets cool. Some of that can be mitigated by having the right socks on the right day. I am going to keep wearing them until they stop being waterproof, but I wouldn't buy them again. They are cute and do come in fun colors, plus you can get them for $56 right now. If you want something that is waterproof and will only be worn between 50-70 degrees they are an excellent boot.