Well, that's my first time hearing they don't give T pills to trans guys. I know for a fact that a bunch of people where I live initially start on them and only later switch to injections. I live in Europe though, maybe that makes the difference. That being said, I can't imagine it would be good for your liver at all, yeah. I don't know about you, but taking pills all the time makes me feel like there's something wrong with me and like I'm sick (not physically sick as in vomiting, but the general "Oh, I'm sick and I have to take pills every day for a long time now"), even if they're just pain killers or plain old iron supplements. (By the way, taking pills at the same time every day is quite bothersome and tiring in the first place, plus there can always be random changes in your schedule.)
Either way, to answer your question, I'd say injections. Where I live, I don't think gel is even used in the first place, and for people in the US, I always see them talking about T shots, not T gels.