Aetna vs. Tufts: Which would you choose?

My new employer offers a choice of Aetna vs. Tufts PPOs. I know we have a few health care workers here; does anyone have opinions about the general quality and breadth of the two networks, access to specialists, and how much "utilization review" red tape I'll have thrown at me? I have a number of chronic, difficult-to-diagnose symptom clusters, and I've been lucky enough to have Blue Cross for 10 years - they'll approve anything once they see a medical necessity letter.