Surprised no one has corrected you thus far. There are actually three main Grading Companies PSA , SGC , and LASTLY Beckett , The 1st thing is what card you are considering for grading but also the reason why I.E. for resell , for authenticity , etc The 2nd. thing is what you look for in grading companies. I.E. integrity , Quality / Closeness of the Grade , Value holds up , I don't mean you get the most at the moment , but overtime the vaules haves stayed the same or gone up for the most part.
Lastly I will say I have used SGC b/c I like the look of there slabs especially when using them on my 71's , Values have been consitent , but most importantly of the three companies they have to me shown above and beyound the most integrity , and also The most Strict Grading.
PSA has had some problems : I..E. the Wagner , insider PWCC and a few other issues not withstanding. That said I still will buy a PSA graded card but as always I would look at the card anyways b/c as has been said before a 100 times your buying the card not the grade..
Beckett : why I can't stand them they tried to act like big money players from the begining , by bad mouthing PSA and SGC , wherever they could non chalantly . Also by trying to act like they have been grading cards forever. Sorry but anyone with any years of age to them in this hobby knows PSA was the first big grading company to finally stick. A few more years down the road then followed by SGC. Another thing beckett does to actually lower standards of grading is they have multiple grading services I.E. Beckett BGS , Beckeet Vintage BVG , Becket idk but will call it vague grading BCCG , then lastly the biggest joke of all the raw card review..
Again I would use SGC , I would buy or trade SGC , PSA , BGS or BVG but only if it's an absolute steal of price or wouldn't want.
Got my collection kind of split up in 3 places in two seperate states. So I am willing to trade but might take me a bit to find the cards from my Trade / Sell list. So please message me first so that I can take some time to find the cards you would be interested in. Whether it's an hour or 2 months or etc. I would get back to you after locating the card or cards.