I just connected at both LAX and PHX over the weekend.
PHX is familiar for me since I lived in AZ for 20 years and flew out of there many more times than I remember. While living there I only connected once, during a mileage run. But since I moved I've connected a few times.
I've connected at LAX on/off over the years. This past weekend was my first experience with the 52 gates (what people here call Eagle's Nest).
For me it all comes down to schedule, price, convenience, and type of aircraft, mostly in that order.
There is also some construction going on in the T4 area at PHX; in the area between the low and high A's. We had to wait a few minutes to pass through. And inside the B terminal looked horrible, with torn up carpets, bare concrete for floors, and construction. It seems there's always some sort of construction somewhere in T4, and moving sidewalks frequently aren't working.
That said, I know I can reasonably make an hour connection at PHX, even mainline to express. The same can't be said for LAX; I had a 2 hour window for my connection there.