Sometimes I'll say it in a very deadpan tone, most often when someone with a completely different sense of humor than me does/says/shows me something that they think is fucking bonkers gut stitching hilarious, and I'm not at all entertained by it, but feel the need to play along for the sake of the social contract. Second hand embarrassment and shame are real. In that case, "lawl," is acceptable.
Over texts or whatever, I never type it, because it evokes images of 15 year old girls twirling their hair and gossiping. If I find something funny, it varies between "lmao," "lmfao," or "ROFL," in ascending order for how entertained I am. That might be some regional shit or my circle of friends that led to that quirk, I realize it's every bit as stupid as "lol," but again, my life has devolved to the point where I'm typing in depth paragraphs on a gaming forum at 2 AM explaining my usage of acronyms to a bunch of complete strangers, so whatever. Lol.