From my experience with having T-Mobile for my personal phone, and Verizon for my work phone, and living on the peninsula, I get far better data connection speeds from my Nexus S (which doesn't even support the full 42mbps HSPA+) than I get from my Galaxy Nexus on LTE. Getting a signal indoors can be flakey for each phone in various locations, but overall they seem to be pretty comparable on coverage.

I still prefer T-Mobile in end though, especially since I'm only paying $50/mo for unlimited everything...