OnePlus One, which originally shipped with Cyanogen, has (had?) a pretty good ROM community. Since this seems to be trying to recapture what people liked about the One, I suspect there'll be ROMs for it soon enough. For right now now, I'd probably still go with the original One, or a Nexus.

Not really, the OnePlus One came with a lot of promise but OnePlus has quickly severed ties with Cyanogen and the support for the OnePlus One somewhat died out when OnePlus switching to Oxygen (if you still have Cyanogen on the OnePlus One you can get OTA updates from Cyanogen).

After that I never bothered with the OnePlus 2, the lack of NFC support probably had more with me not buying it than the OS support but that also played into my decision.

I have a OnePlus Two, and yes, there are CyanogenMod builds for it, I've been running them for the past year. Just last week, the updates started coming through the in-OS updater, rather than me having to download and flash ROMs. I haven't been bit by any bugs or even particularly rough edges for the past three months or so.

I assume these builds will eventually get blessed by CM -- maybe they already have?

The thread I keep an eye on:

http://forum.xda-developers.com/oneplus-2/development/6-0-x-...

Ish, but as they open-sourced their driver, I expect a much more growing modding community. https://github.com/OnePlusOSS