I see AROS as the natural progression .....
OS4 is the natural evolution, the future. Try it, you will love it :-)
Aros is a good alternative, free and slowly but steady updated.... and i don't think MOS is dead anyway.
Be positive, OS4 is amazing, AmigaOne is not cheap but our market is still little. Anyway if i bought an XE everybody interested should be able to do it... i'm a very poor guy :-)