Try them and see which you like best. You can test AROS easily enough on your current virtual machine. Depending on your hardware you might be able to dual boot into the native version.
Which flavor to pick really comes down to a combination of taste and what you want to do, and how much money you're prepared (or not) to invest.
Absolutely, give what you can a try. All are more similar then these previous posts would tend to indicate.
Personally, I'm using MorphOS because it is the most polished of the three NG OS' (and it's cost of entry is lower than AOS4.1).
You can get a Mac that willing run MOS for under $100 and everyone I've talked to who has tried it has come away with a positive impression.
