Both!
Nolvadex prevents estrogenic activity at the breast site. This is why it's prescribed to post-op breast cancer patients. Keeping activity at the site receptors to an absolute minimum greatly slims the chances of cancer re-development. This is crucial coming off cycle too, as more than likely homone levels will be like a rollercoaster to some extent. Keeping estrogen from acting up in the breast site will prevent gynecomastia development, but allow natural test and estrogen levels to even out on their own.
Clomid fires up the pituitary side of the HPTA, starts sending signals to the balls telling them to produce on their own again. Taking it for 4-5 weeks at 50mg post cycle generally does the job. Getting bloodwork done 6-7 weeks post PCT to see where test levels are will ensure the Clomid did the job. I've heard of individuals having test levels up to 1100 on Clomid before.. it's not to be taken lightly, it's the bomb. In fact, many will use it alongside their suppressive SARMS like S4 or Ostarine, and keep their natty T blasting away instead of using injectable test to make up the difference, food for thought there.
In my opinion, Clomid is the most important of the two for post cycle recovery. At the end of the day, you can have your mammary glands removed from gyno development.. once your balls quit working.. good luck getting them going without Clomid. Even beyond that, they may not work ever again depending on the lengthiness of the testicular shut down with or without Clomid restart attempts.
Moving on! One thing that I feel should be added to this.. is how ridiculously important it is to have HCG for recovery as well! There are two sides to the recovery loop that can be manipulated to help an individual get their natty production back. The balls, and the brain. Clomid covers the brain post cycle. HCG covers the balls during cycle! Not only does HCG keep the balls in a semi-active state (by disguising itself as leutinizing hormone in the male body) during a cycle, or time of suppression.. it also will help to maintain their size. I advise readers here to invest some time into learning about modern TRT methods and how HCG is used during their regimens.. it should be mimicked for anyone using AAS hoping to recover post cycle. Helps with fertility too. Most I've seen run HCG at 500iu's a week during cycle.
Combine HCG and Clomid for a potentially flawless recovery of natural test production, post cycle.
Also, I am Hypnotix from Steroidology.com, I was invited to this forum through an email I believe from PSL, a sponsor on my other forum! Hope I've helped!