I would recommend the EOS 550D just because it is cheaper. It is identical to the EOS 600D in every way except for the tilt and swivel screen. This may come in handy when shooting video or taking shots from high up or really down low. You have to judge for yourself if this alone is worth the considerable price upgrade.
If it were me I would get the EOS 550D and a really, really nice, fast, lens.


