Mac and Lisa stuff has been my main focus for a long time. Right now I a few vintage Apple desktops and laptops from various eras. As a teenager I had much more; my room was full of old Mac systems. To make a long story short, due to convoluted circumstances there's a ton of stuff I ended up losing. I consider myself lucky to still have my Lisa 2/10 and my 17" iMac G4. The G4 is a real ship of theseus - I've got it in 08 as a birthday present and have since replaced the hard drive, optical drive, power supply, motherboard (1Ghz USB1 -> 1.25 USB2), the RAM, and the bottom panel. The neck is sagging a bit so I'm gonna have to tighten that soon. My original computer from when I was six was a Rev D 333 blueberry iMac my parents bought me. Sadly I don't have it anymore, but it was on it's last legs anyway...
I've also played around with a number of Windows systems here and there.
At this point in my life I realize the need to be very careful and selective about what computers to buy since everything ends up becoming a project that takes time, money, and resources. I think if I was going to get another machine, I'd want it to be something serivcable, where modern part replacements and recreations exist. I'd also want something that has software I'd be interested in running and using - otherwise what's the point! I've been eyeing the idea of getting some sort of PC all in one, maybe an IBM model 25? Maybe just something I can use to run older GUIs like Windows, GEM, VisiON, etc, and that will look good next to my Lisa and my Mac Plus. Really, it's all about what I can fit into my apartment without going insane, and that won't cost a fortune to keep in working order.