I think something similar to AROS in the way it's not bound to particular hardware and runs on multiple archs. The ability to run my old classics without having to think about it is also important to me (including custom hardware hitting games). Unless someone comes up with some sort of "amiga on a card", then this is obviously going to be emulation, which Im fine with so long as the experience is reasonably seemless. Apart from those, basic OS structure I like, so that has to be much the same for me. Being able to know your system inside out as well. Datatypes I like the idea of still, and have the potential to be everybit as useful with modern computing as it was 20 or so years ago, albiet they'll need to be slightly expanded/freshened up. The apis need to be improved/extended/etc. too, but I do like the idea of the amiga still using it's own rather than adopting something from the open source world. This isnt to say there should be no SDL, Allegro, GL,etc., theyre quite useful and are standards amiga os based systems can join in the rest of the world with, but intuition, ahi, mui, p96, cgx, and so on I'd like to see enhanced rather than thrown to the wayside for something easier/generic.
In a nutshell I guess the direction the "NG" systems are going isnt too far removed from the direction Im interested in. The biggest problem I guess with this road though is that it'll take a lot more time than adapting generic OS components. For me though it's a little pointless to do the latter as I dont see the point in anther OS that has nothing unique. Sure, it's outdated in some areas, but it is different to Win/Lin/etc.