Thanks for the recommendation and advice! Really appreciate it.
I do not worry about the user interface, as I can always find the setting I need on both system. Of course the 550D is beginner level DSLR, so it doesn't have much short cut button like D7000, and because D7000 is mid-range DSLR, and it offer more details setting than the 550D, the most important thing is, both camera take picture!
I feel like go back to Nikon mostly because of the direction of Nikon for their DSLR and the quality issues for their products.
I will move to full frame after I build up the lens and flash that I need. I mostly shoot family photo, and of course will carry it whenever I go travel. I mostly shoot people and some landscape.
Nikon seems preferring to make camera they want rather than what user needs, put D4 aside, I don't think my Computer "afford" to manage 36mega pixels files, the D600 is just another full frame DSLR will all AF points "gather" at the center. Quality issues are also another matter that worth to consider.
Canon DSLR and lens are mostly made in Japan, compare to made in China and Thailand products, I prefer Japan. That's one of the reason I choose 550D initially, but it let me down...
Canon full frame seems a better choice that suit my needs, except the expensive 1DX.
Of course, no one can tell what will both company offer in future, but let's say in this 3-5 years time.
I understand that no perfect camera in the world, and I'm not looking for perfect camera either. But just need some opinion from You all.
Thank you!