User Activity

If you could only have 3 lenses, what would you choose and why? Also, which focal lengths would you recommend for landscapes, portraits, and architecture? I know I need a wide angle, but am not sure what else. I don't have the money to buy 4 or more ...
I've been using an OLD  rebel EOS for years and am looking to upgrade. I need a camera that produces pictures that can be blown up to poster size or even bigger. Also, i'll sometimes be using the camera in low light situations.  Obviously, i'm trying...