As already discussed, kinda depends on what you want to do with the gun.
For proper 10-meter target work, go for a flathead wadcutter match pellet. Vogel, RWS Meisterkugeln and R10, H&N Match in rifle and pistol weights, and JSB Match are all good ones that I've tried. Flatheads are also very effective hunting ammo for small critters (birds, mice) at short range. Match pellets usually weigh a bit over 8 gr in rifle weight (due to curious international rules dictating they match the weight of a 4.5mm lead sphere), and 7.5 gr or so for pistols.
For longer-range work, go for a round-head that will fly a little flatter. I don't have much experience here compared to many on this forum, but like the 7.3 gr Air Arms Falcon and 7.9 gr JSB Exact in mine.
I'm actually not a big fan of Crosman pellets in springers in general, but haven't tried them much in FWB match guns.
Some match pellets are available with different head sizes, varying by thousandths of an inch. Another thing I've never played with, but I'm guessing this doesn't make a very noticeable diff outside of competition shooting. Not something I'd worry about when sussing out a new gun.
You will find that most pellets actually vary much more in their skirt diameter. Crosmans tend to be small, RWS tends to be big, and most are somewhere in between. This can affect velocity, consistency, and "feel" of shooting the sledge FWB system to a surprisingly noticeable degree.
Any gun will have its own preferences. I have an old model 300 that shoots well with just about anything that I stick in it, but my 300S's are surprisingly picky. So, have fun! Playing with different pellets is really pretty interesting, you will enjoy checking out different ones and seeing what they can do. You certainly picked a great rifle to start with!