I keep wanting to argue for something between GotG and LotR, and then I keep adding caveats that drag it back towards the sillier side of that middle.
Really, it's just that I try to present realistic goals, stakes, difficulties, and people to interact with, and it's not my goal to be funny. Once the actual adventuring parties interact with those things, it tends to default to humor. I'm definitely not above putting in a comic relief character or scene myself every so often though.
I went with "mostly serious, with moments of levity" in how I design my adventures and run my games. But in practice my games can be more humorous than that - a lot of the humor comes from the PCs and what they do and say.
My campaign setting is like tv. I borrow, beg and steal from tv, books, movies, comics and every other type of storytelling I encounter. To that end, some of my games are drama, and some are farces. Some are high brow, others gutter dwelling. Some are popcorn movie action, and some are mysteries.
I begin a new group with a few sessions as a diagnostic. Then I use that inform ation to set a goal for how I'll balance the game around the style of the payers - but I try to sample everything. There will be family drama, action, mystery, comedy ... all of it - just in different ratios.
In the past, my games (not just D&D, but in general) have tended to be Mostly Serious, but more recently have leaned to Lots of Humor.
I think this has less to do with the game itself, but the role the game plays in our lives right now, and how it fits into our schedules. When you only have a few hours every couple of weeks to play like this, leaning to humor just makes the play more effectively playful.
Consider I'm primarily playing Starfinder, but my game is closer to Traveller with some fantastical elements. There might be more levity, if the basic setting was less grimdark, which tends to engage more serious play. Clever quips are always present, but since the setting isn't wahoo, the game tends not to discintegrate into a farce of comedy. Just when laughs are peaking something dark always happens to bring back the seriousness of the situation.
Echoing what @Lanefan posted in comment #10: "All of the above."
But I guess option 3 "Mostly serious, with moments of levity" would encompass this best, but still doesn't give the full picture and sounds much too mild and middle-of-the-road compared to what we do. Our campaign varies from from extreme Lovecraft-inspired horror and world-wide and personal catastrophes (misery) to high fantasy (serious) to hilarious comedy moments (humour) to even not-at-all-serious adventures that certainly ventured solidly into Monty Python territory (complete farce). Oh, and let's throw in soap-opera worthy sappy romances as well ...
I do a straight plot as a base, but both the players and I generally have a bunch of humor in characterization and how things turn out.
My D&D games usually go for and often achieve a very Army of Darkness tone, action horror comedy at a PG 13 level. Not Evil Dead R gory horror, but PG 13 deadites who get decapitated by a jerk with a chainsaw. Give me some sugar baby and some innuendo, but nothing graphic.
In my current game two of the PCs are members of the Acme cult, so there are lots of reskinned spell effects to be anvils and dynamite. The robot (reskinned warforged) arfiticer has a techno alter self spell/tech effect to make himself look human and describes himself in disguise as a meat popsicle (5th element quote).
I have embraced failing forward for this current group.