Bilbo,
I too would put PCI in the second tier as well as SEGS. Both are liberal on moderns but relatively solid in grading classics. They are both true TPGs in the fact that they have a physical address, accept public submissions, and are not a way for some shady guy to sell his own junk coins. However, outside of those two and the Top 4, those are waters that I do not wish to wade into, lest I drown in a sea of incredibly overgraded, cleaned, damaged, and possibly counterfeit junk
