LOL nice avatar.
Personally I go with PSA, but Chad is correct in some ways. SGC just doesn't have the mass love that the others have.
Stick with PSA, SGC & BGS for cards that will hold their value and are respected by collectors. The others are just pretenders in that the number on their slab does not often match that of the true quality of the card. The above companies are the best at accurately grading cards, though I have seen cards that have been over graded by these companies. That being said, I have seen cards that have been under graded too.
All that being said, my motto is BUY THE CARD, NOT THE GRADE. Meaning don't just buy a card because it says it is graded 10. Look at the card and make your own call. Ask for better scans if you have to.