I have only done cream/gel. Transdermal, injection, pellets, sublingual and patches mostly bypass being processed by the liver, unlike the pills which I've heard are a bit harder on the system and more likely to cause blood clots.
I'm over 40 and had a history of drinking, so I'm playing it on the safe side. I'm also getting the orchiectomy very soon so I can do this with the minimum amount of pharmaceutical assistance.