Which is better? Oh Baby seems to have higher DPS, but according to the fallout wikia thermic lance has higher base damage and is continuous, so shouldn't it have higher DPS?

It depends how often the thermic lance inflicts hits - if it's at a slower clip than Oh, Baby! than obviously the DPS will be lower. This question seems quite focussed, other weapons can be better at doing each of those individual weapons' jobs.

for me Oh, Baby! was easier to use than the thermic lance. try both.... Oh, Baby! can be obtain via a quest. and sometimes SL has a gotten a TL for free. so try both and see which one you like better.

Personally prefer Oh Baby!

I have both and have used them, the damage is just confusing the hell out of me. I'm probably going to stick with Oh Baby! since it's just so damn satisfying to turn someone into red mist.

when in doubt use what works for you, i still dont bother using the thermic lance and just prefer to obliterate everyone who disagrees with me with a good chainsaw to the face.