What is your current protocol? Hcg won’t prevent you from being shut down. Hcg mimics leutenizing hormone which is a hormone that tells your testicles to maintain their size via leydig cell regeneration and synthesis. It’s certainly better than nothing, but fertility isn’t just about LH, but FSH, follicle stimulating hormone as well and hcg does nothing regarding fsh.
Nolvadex is likely slightly better in whole because it blocks estrogen, specifically in the pituitary and hypothalamus (as well as breast tissue cells which is why so many use it in gyno prevention) convincing your brain to pump out LH and FSH themselves. 20 mg per day of nolvadex should do the trick unless you’ve been shut down for an extended period of time.