I think, knowing you're not a terribly technical person, a second hand Sam 440 is the best option for you.
They're cheap, stable and very economical with power, well supported and easily fast enough to play around with. The only downside is that they're too slow for demanding apps or videos, but you can always upgrade to a faster machine if you feel it's worth the money.
I recommend getting an SSD for it instead of a normal hard disk, then they're silent and really responsive.
AmigaOS 4 is very cool on classics, but I can't recommend it unless you already have a PPC card, and it isn't really suitable for those of us with less experience.
