I can't deside what DSLR to get

A Canon Rebel t2i with a 18-55 m lens.

A Canon Rebel t2i Body with a 50mm f/1.8 II Lens.

Nikon D3100 with 18-55mm f/3.5-5.6 Nikkor Lens

Which one's the best for a beginner? If none, which one should I get?

Go to the store. Hold both cameras in your hands. Buy the one that fits you hands best.

I would go with the t2i, I'm not to sure about lenses, I've been told that a 50mm is a pretty basic lens. The T2i has amazing picture quality especially for the price (under a $1000 which for a professional camera is great) I actually want one myself. I've used the t1i and I loved it but the quality of the t2i is considerably better.

If you where looking at the Canon Rebel series and expected to spend around $900 then why don't you check out the new D5100 from Nikon. This camera has the sensor of the new D7000 DSLR but in a D3100 body. It has the vari-angle swivel LCD and works wonders in the video side of things recording 1080P at 24fps with continuous auto focus within the video. If you can get this camera with the new AF-S 35mm F/1.8G and the AF-S 50mm F/1.8G lenses, that is all that you need. Prime lenses will give you better results and faster focusing due to the low aperture rating.