Honestly, if I couldn't wait, I'd go with Neon. There aren't many other options anyway. Other considerations could be Arch or KaOS. I don't know the timeframe for openSUSE Tumbleweed, however, they are usually super fast. It could be a matter of weeks when Plasma 6 will be offered if it's isn't already. If I could wait, Kubuntu 24.10 seems to be a reasonable choice (or any other distros you would consider that will ship Plasma 6 this year).
I wouldn't go with option 1. As far as I know, thy don't offer Plasma 6 yet and I don't know whether backporting Neon repos will work.
Fedora 40 KDE is pretty solid as it is already. I actually moved away because Gnome completely fucked it up by banning any 3rd party screen shot app based on the Apple mentality of "its for your protection", which is total bullshit.