Several of my mom's neighbors and friends have had knee replacements over the last few years. They have all had the "stryker" knee replacements and all of them have done well.
Mom had one knee done last year. Her recovery period took quite a bit longer than the others, but she is doing great with it now. She needs the other one replaced. She is trying to build up the courage after the last one...lol. I think she'll actually do better the next time, but I know the mindset is tough to break. The therapy and recovery begins immediately (same day or next day after surgery). It is painful and strenuous. Some actually do both knees at once...that's a tough gamble, but if you can handle it, probably the way to go. We weren't sure mom was strong enough to do both at once though.
At least in our circle of friends, "Stryker" seems to be the replacement of choice.