In my opinion, hCG should be part of every TRT protocol.
It's benefits go beyond preservation of fertility. HCG allows the testes to remain functional, something that is lost when using exogenous testosterone without hCG. The testes have many roles, sperm production is only part of their job description. The testes aid in the production of other hormones, so it's a no brainer for me to keep that going.
It will also prevent testicular atrophy/aching caused by exogenous testosterone. Not everyone experiences the aches or discomfort, but those who do very much appreciate the job that hCG does to combat it.
I am on hCG which has been prescribed by my doctor, and I've only experienced positive effects from it.