According to me, limitation = you cannot rest when you want to.
I don't want strict mechanical limitations.
I kind of like the food supply mechanic even if they could really overhaul it (There's something between "food limitations" and "food overdose").
Random encounters and long rest location doesn't prevent you to rest when you want to.
SO I vote "no limit", food supply, random encounter and rest location. In my opinion it's not incompatible.
I also like the "time sensitive exemple but to me it has nothing to do with "limiting" long rest. Kingmaker really limit long rests through timed events. And I really don't like it
Yes. I don't want hard long rest limits either. For time sensitive events, the hard time limits would be only where it makes sense. Like Waukeen's Rest. It makes no sense once you see the burning building that if you long rest it's still burning. Likewise, it makes no sense if you trigger Minthara going to attack the grove that night, if you long rest, she still hasn't attacked the grove.
But I totally agree. I don't want "You have 5 days to defeat the goblin leaders. If you don't do it in 5 days, game over."
I also agree that multiple "limiting" elements make the most sense for long rest. They need to cut down on how much food you can find so it's a bit more restrictive and therefore a bit more meaningful that you might have to conserve your resources. I also like rest locations and random encounters IF, as we've discussed before, the encounters are done well. No trash mobs please.
I also think random encounters would be good for fast travel limitations, but that's a whole other topic.