Nolva is more effective on a mg/mg basis at raising natural testosterone levels than Clomid is. I use HCG/Nolva/Proviron for my PCT, avoiding Clomid all together.
Many peoples PCT varies. Some have positive effects off Nolva only, whilst others wont and will run Clomid/Nolva.
This is from Hooker's Profile on Nolva, found here:
http://forums.steroid.com/showthread.php?t=199821
"Nolvadex also has some important features for the steroid using athlete. In hypogonadic and infertile men given nolvadex, increases in the serum levels of LH, FSH, and most importantly, testosterone were all observed (2)(3). The best (rough) estimate I can give you from my research is that 20mgs of Nolvadex will raise your testosterone levels about 150% (5)...and this would of course greatly aid post-cycle-recovery. What this means to us is that if you take Nolvadex after a cycle, when you are trying to raise your levels of testosterone, LH, and FSH back to normal, it will greatly aid recovery. In fact, if I were limited to just one compound to aid me in post-cycle-recovery, Nolvadex would be my choice. If you want a comparison, it would require 150mgs of Clomid to accomplish that type of elevation in testosterone, but nolvadex also significantly increased the LH (Leutenizing Hormone) response to LHRL (5), after 6 weeks.
Some of the more harsh ancillary compounds available today will give you a more “dry” look that nolvadex can’t, but nolvadex is simply safer to use in long (over 16 week) cycles."