There are plenty more of these threads, and actually this one is a couple years old. If I find one that's newer and as long and useful I'll add it.
Lists like this are highly subjective of course. I've always been the sort of gamer that finds value in things others find useless and vice versa. But you can get a feel for things you should carefully consider before pulling the trigger.
Some of the biggest repeats are
-- Yacht. Didn't need to read the list to figure this out. The ultimate GTAO vanity purchase. I mean, if you have millions and millions and nothing to do with it then, yeah, still don't buy it. You'll regret it. Maybe if it functioned like the Terrorbyte it would be OK?
-- Motorcycle Club. A bit of a surprise, and maybe they've since added better/more useful content. But the number of players that list the MC was revealing
-- Stilt Houses. The thing I think most people hate is the fact that the garage isn't attached, no way to go straight in from the house. Plus they are less convenient to get to.
-- Crate Warehouse business. It's a pretty good money maker, so the fact that it appears so often shows how boring the actual missions and running the business must be.
-- Lowriders/Benny's stuff. It didn't interest me from the start, but a lot of players regret spending money on lowriders. One guy said a million a pop. Is that what these cost? Good grief.
-- Hydra (GTAO's Harrier). Big Surprise. I see a lot of these when playing. I think if you aren't out to disrupt others, there's little reason to get one.
-- Swift Deluxe and Luxor Deluxe. No brainer really. No better than the cheaper variant and even those kinda suck. Waste of money
-- Rhino tank. Seems cool until you realize there isn't much use for it I guess.
-- The rest is an assortment of various weapons, vehicles, clothing and that sort of thing. No single thing will be valued by every player. But for any of the above, think twice before pulling the trigger
Animals flee this hell, the hardest stones cannot bear it for long. Only men endure