Which one should i go for? (professional cameras)?

So i'm not a photographer, yet. I'm just into the photography thing and i want to get a camera but i'm confused cz i've always wanted the Canon 550D but recently i've looked at the Nikons and think they're a bit less complex for me. So if any of you know and understand anything to do with these cameras would you explain to me the differences, which one is better and long lasting more than the other? Thanks.

my choices are CANON 550D, NIKON D90, NIKON D3100

Well that is a hard one. Mainly because I own and use both Canon and nikon cameras. Lot of times it boils down to which one I grab first.
Then a lot of times I'll have my telephoto lenses on one and wide angle on the other one and the shot detemines which one I use.

Of the three they are all good cameras. Just get the one you personally like the best. You can't go wrong with any of those three.