PCGS and to a lesser extent NGC are the top grading companies. there are others that are good but those are the best brands/most liquid. increasingly people only want pcgs, especially for higher value items like yours.
That's an NGC holder and they are a top-tier grader. They price guide has the 1904 between $2300-2600 for MS63. It's actually a common date and most of the value is indexed with the price of gold.
agree NGC is a top company. however, you get slightly more when selling PCGS over NGC. There is a huge difference between PCGS or NGC and the others, however.