Resolution of camera

More resolution is not necessarily a good thing.  The Nikon D5100 has a slightly larger image sensor than the Canon T3i and so it has slightly better image quality.  Having said that, for personal use either camera will suit you just fine.  I would suggest you get whichever you can find the best deal on.

You really should base your decision on other factors rather than the resolution. Both has plenty of resolution for general amateur photography needs.  It's like saying I'm buying a Chevy just because it has a bigger engine than a BMW, total non-sense.

Both cameras have more features than most amateurs will ever fully use.  While Canon has slight edge in resolution, Nikon has better overall sensor performance, not my words, but the conclusion of the experts at DXO Labs.

Most useful thing you can do when deciding is if possible, check out both cameras to see how they feel and handle in your hands.  Check out the button locations and user interface to see which one feels more intuitive and comfortable.   In terms of overall performance, they are similar, although I'd give a slight edge to D5100.

t3i is as good as the Canon 7D with regard to resolution and image quality. You would not be disappointed.

Try the new 650D it has a better resolution than the 600D.