Both are very nice cars, but it will come down to personal preference and what you want to do with the car
If you can't decide, list some pro's and con's. Eg. R34 has more aftermarket support, V35 is a newer car etc. Personally, I went for the R34 as I like it better and its more in line with what I want to use the car for. Also, having more aftermarket support was a big plus.