Fly is nice because of the bullet proof construction and the quick connect fittings. Launch pad is nice because of the link (check valve) system built in. They are cheaper as well. You cant beat Skylon sacs on the price but the fittings aren't my favorite but they work.
Pro X Series are rock solid... and for a pump buy rule pumps you can get a 4000 gph for like $125 and thats over a gallon per second... you do have to do a little pvc mod to make the 2" outlet fit the sacks, but its really really fast and not to pricey