D90 user here
i was actually thinking of getting a 550D or D90. the feel and ergonomics sold me on nikon.
my unit works really well with sigma lenses (sigma 18-50mm f2.8, and the sigma 30mm f1.4.)
unfortunately the nikkor 50mm f1.8 was too soft on my d90. hindi sila match nung body ko.
now, if only i can get a nikkor 17-55 f2.8 para ma compare ko.