hi everyone, first post

I'm thinking about getting a secondhand canon 5d or d300. I've done my research, and since d300 is newer, sturdier, faster, more accurate and most importantly I have dx lenses from my old nikon d50, I should buy d300. but..

there is no problem with d300. the problem is 5d. when I compare full resolution examples from both, I see 5d is sharper at pixel level and there is something that attracts me to 5d's example, but looking at d300's photo I can see no faults, perfectly clean and noise-free image and crisp edges and good contrast and detail. but when compared to 5d, d300 looks.. flat. I don't know any words to describe this difference, nor am I able to see in technical eye. Can you explain it? I know 5d is full frame, but would ff make that much difference? Which would you advise me to buy? after all, I'm a nikon shooter and have nikon gear(albeit only two lenses, one being kit and one 50mm) and I like nikon sturdiness, but when it comes to that, quality trumps it all. I also wont do sports shooting or anything about speed. I know there are much better alternatives today, but I don't have enough dough for 5d mk2 or d700 Since this is the canon forum I don't really expect people to vote for nikon, but really, what's that difference that I can't see? it's obvious, but I can't name it. does anybody have an idea?