The Geforce 4 ti 4200 is the better card. Particularly if you get the 128 meg version. Whikle the 64 meg version is faster, it actually doesnt perform as well in the long run and will suffer a performance hit because it physically lacks the amount of ram.
Whether Gainward is the best really remains to be seen. I personally would go with an Asus Geforce 4 V8420 Deluxe. The Asus deluxe has faster ram which actually equates to about ti 4400 speeds
You also might want to consider the brand of motherboard you have and also the overall package you choose to buy some cards come with games you might find boring. Or they might lack a connector you might want.
If its not broke dont fix it.