I am not a dealer, just a lowly collector who recently switched from PCGS back to NGC because I am sick of spending too much money and waiting forever to get my coins back.
One of the other primary reasons I had for switching was that I feel very strongly that PCGS undergrades as a marketing technique. If you feel that PCGS coins are "better", the reason is that you are really paying less for the next grade (or in some cases 2 grades) up.
Obviously this isn't true 100% of the time, but my experience with PCGS is that I assign a coin a grade based on all the standard references and it consistently comes back one grade lower.
Perhaps you think that I am simply a poor grader... Well, that is definitely a possibility, but I do find I am right on the money about 95% of the time with other grading companies and my local dealers.
The bottom line is that you feel like you got a "steal" because you know you just bought a F12 in a VG10 holder for a premium over VG prices. You can either embrace their philosophy or reject it, but either way it is the same coin regardless of the plastic that is encasing it.