Im not seeing much benefit in running the "next gen" stuff, but of the options, AROS is the only way.
Its open source, so it can't be taken away, and there's very little cost of investment.
It may be behind Morph or OS4 in some respects but it has room to grow. Morph seems cool but it has no place to go. (they could port it, but given how long and still no laptop support or even basic stuff like wireless, I kind of doubt they can pull that off)