Trump is an unserious answer because and only because he hasn't even been out of office for long enough to need a new toothbrush. I fully expect that in the longue durée his energy policies alone will be viewed more harshly than any policy of either of the other options with the possible exception of Reagan's inaction on AIDS. However, since that hasn't happened yet, Reagan is my answer.
I've been dogpiled on in some circles for making unambiguous my stances on Reagan's AIDS policy, and there are still plenty of people who see it as a political inevitability vis-à-vis the stigma of the disease, even though his leadership is exactly what would've been needed to break through such prejudices. Similarly, I imagine that many circles in the oil emirates of the nation will still be fondly looking back on Trump's energy policy and cursing Biden's one offhand remark about divesting from oil even once ecological consequences become insurmountable, although public opinion will probably gradually keep moving in the right direction on both issues.
This is going to sound much more pessimistic than my usual posting style but I'm of the opinion that ecological consequences, at least in my drought-stricken little corner of New England, are already insurmountable and have been for a few years now. The Doomsday Clock should be set at zero; the conversation should turn from preventing catastrophe to living in the aftermath of catastrophe, which
is still possible and even likely (in other words, I'm not freaking out about total human extinction or whatever). Serious body blows to our post-industrial way of life are unavoidable now.