"Dream plane" is a hard thing to define. My brother and I had this discussion when he started showing interest in RC and I share many of his views. As I see it, there are a few different reasons for/categories of a dream plane.
-What do you want to SEE fly
-What do you want to BUILD
-What do you want to OWN
-What do you want to FLY YOURSELF
And possibly another category of, what do you want to tinker with until it works perfectly.
I would love to see a giant B-36 droning around the sky, and it would be neat to build and fly one, but I have no desire to own one or deal with any of the hassle involved with storing, transporting, or maintaining it. There are a number of hyper-detailed or very large planes that fall into this category for me.
I wouldn't mind owning and flying a PBY Catalina, but the practical issues of owning it start to sour the "dream" aspect for me.
I would need a new flying site for it and somewhere to store it at the very least.
It's not an exciting thing, it's not big or flashy or super-detailed, but for me a UMX Curtiss JN-4 would be tons of fun. I don't necessarily want to build it, but it would be easy to store, there are tons of places you could fly it, and it would look great skimming along at eye level looking all barnstormer-y. The only problem with that is, they don't exist, no one makes one.
I think what I'm interested in is what makes your dream plane a dream plane for each of you? What would you enjoy about the planes you choose?