Two things influence the flavour really strongly, fat and aging. Overaging requires careful cooking.

The tastiest hamburger meet I ever had sat out unrefrigerated for a day. When I opened the package the smell just about knocked my socks off. As I had nothing else to eat at the time I fired it into the frypan and thoroughly cooked it. Smell went away and the taste was awesome.

Of course most people never really taste the beef they eat because the true flavour is disguised by either BBQ sauce or gravy. I by beef from the same source all the time and never put anything other than salt on it. Maybe 2 or 3 times a year I'll get a piece to die for. The flavour is exquisite.