Consider what kind of resources are available for the platform too. I have an 800XL as my only in use retro computer, and between stores like Best Electronics still selling replacement parts and new old stock, Atarimania with an exhaustive library, Antic Podcast, and all the information on the system here, I've had a blast with it despite never having owned one or even used one in the 80s.
Other computers may certainly have similar resources, so I'd suggest seeing what there is to support the system you're leaning too - it certainly increases the fun factor.
For what it's worth, I had a C128 in the 80s. The Atari still captures enough of the period nostalgia to scratch that itch too.