I have a Leadtek Gforce4 Ti4200. I think they are great. Some Gainwards are known to have problems, I am not too sure about Gainwards, but I do like Gainward cards equally as I like Leadtek.
I have the 64Mb version and actually I have two of them in two different machines. The first one does not overclock well, it can only do 285mhz Core GPU and 610mhz on the memory, but I still get 12,600 3d marks with it running an overclocked Pentium 4 1.6a @ 2.5ghz.
The other machine is running my other Gforce 4 Ti 4200 perfectly at 305mhz Core GPU and 605mhz on the memory. I get 7800 3d marks with a Dual Pentium III 1000mhz (133) setup Abit VP6. I am going to swap the cards out.
I had the best luck with Leadtek cards. I have a Gforce3 Ti200 from leadtek and I was able to overclock without any issues from 175mhz Core up to 220 perfectly and from 400mhz memory to 520mhz.
The best thing about leadtek was the warranty. I had fried my first Gforce 4 Ti4200 64MB. I removed the HSF unit to expose how poorly the thermal goop was applied by the company. So I was able to RMA regardless if the HSF was tampered with. Leadtek is great!