If we're talking high end, the SBTs and O/Us from Ljutic, Seitz and Alferman come to mind. These are high volume, precision shooting tools made like Swiss Watches to very tight tolerances.
Alferman O/Us run over $30K. Ljutic Bi-guns are not far behind.
Kolars start around $8K. Kolar owners are a very happy lot. New Kolars are fit at the factory to the owner.
The stuff from CT Shotgun is superb, though as much for pretty as for shooting.
If we're talking production guns for use in the field, range and as needed elsewhere, the 870 triumphs again....