If you lack time it's better you focus on a single machine, otherwise you'll spend more time configuring and installing stuff instead of using your favourite OS.
Yes.
My favourite would be AOS4, but to me it needs more tuning.
I have a hunch that with very minor tuning MOSmini can act as my main machine.
AEROS would provide a peek at AROS + mandatory mainstream+work apps in Amigish environment.
AOS4 would be there to play with & see how far it has come. (it can also provide firefox derivate if needed, sure, also AEROS can do it)
AOS3 for some madatory 68k HW enjoyment + authentic retrogames, etc.