All the fancy shapes are just gimmicks to sell pellets to folks much like you. However, those of us with a bit of experience will tell you that the round domed pellets are just fine, and shoot better. Shot placement is more important when dealing with airgun velocities, and domed pellets do better at that. If the Crosman premier pellets shoot well enough, and made in USA is important, then go with them. Otherwise, I'd go with either JSB Kings or H&N FT Trophies. Be aware that the velocity label on the H&N pellets should be followed. Fortunately, the Marauder makes it easy to tune to any level you desire.
Just for reference, in England, most airgun hunting is done with airguns that produce no more than 12 ft-lbs of energy at the muzzle. Rabbits are a common critter and these are often taken in excess of 50 yards. So, don't worry about the velocity of the H&N pellets seeming to be too slow, they will kill squirrels just fine, especially in .25 caliber.