I am a Herter's fan. Nothing beats a burlapped foam decoy. They're indestructable, can take a brutal beating, and ride the water like a champ. Doesn't take much current to move the decoys on a wind-less day either. Don't have to fret if you get a few pellets in them either. Not to mention they're very lightweight, almost like a feather. They're not cheap but they're not ridiculously overpriced either - they're a good investiment and will last a LONG time.
I prefer to target diver species, so our decoys are hand painted to look like canvasback and bluebills - they give off a lot of white which catches the birds' attention and draws them in.
Greenhead Gear decoys are decent too, they're very affordable, but you get what you pay for. They fall apart fast. The paint chips off them easily, if you shoot them they will take on water and sink/tip over - and you need to patch them. Plastic cracks easily too. If you don't duck hunt often and are extra careful they will serve you just fine.
Baby mojos weigh less than a regular mojo and take up less space in the boat - but other than that there is no true difference, it's mainly just a marketing gimmick to sucker people in to spending money.