Hard to pick a favorite in 55+ years. I've got several of the early Monogram aircraft to build again. Revell re-released a couple of their 1956 1/32 cars, that I had built, a few years ago. That brought back memories, so I bought them. I built a couple Lindberg Stukas as a kid. Saw one of those a while back, and got it. My stash goes back 25 or 30 years. If I build something out of the early part of it, would that be nostalgic?
These were all built when I was a kid. You can see minimal painting, tracks, headlights, water lines on ships. My kids played with them, also. I might try to restore them some day.