I doubt you're going to get an unbiased opinion here. We picked up our 08 EL October of 12. I looked into Tahoe and Suburban as well. I really wanted a 3/4 ton. But the prices of the GM's was a deterrent. The final thing was the folding 3rd row in the Expy. It's a lot more convenient then having to remove the seat entirely. I've put almost 20k miles on the truck with no issues. Just oil changes, plugs, and fuel filter.
What he said!
I put 100k on the 07 Expy EL with no real problems until the ball joints earlier this month. (Can you really complain about ball joints at 140k on PA's crap-tastic roads?)
The cost and third row sealed the deal for me. You pay a premium for the Suburban. The third row is inconvenient at best and I don't think that they have all independent suspension (good or bad, depending upon your preference).
One thing not mentioned is that the gas pedal seemed smoother on the Expy than the Suburban/Tacos that I have rented. Their gas pedals were very stiff. I think the all-independent Expy rides better too.
I figured out the squishy brake issue so that can be solved on the Expy with better pads and rotors.
As far as efficiency - how much does 19 vs 18 mpg matter to you? They are both bad.
I like the way the Suburbans look and I think the interior is nicer (they have a REAL oil pressure gauge), but I like everything else about the Expy better.