Obviously flat handlepasses are the easiest. I.e. 360 handlepass of a wave with no invert.

On inverted handlepasses, I base my logic on wakeboarding and which is more difficult. Front rolls are far more difficult that backrolls. frontside handlepasses are more difficult than backside.

I.e. Easiest to hardest (this is normally the order you would learn in wakeboarding). In cable wakeboarding for example (which is similar to a nowhip inverted handlepass, slim chances are one of the most difficult to do, and the first inverted handlepass people learn is a KG

KGB = backroll with backside 360
Mobe = backroll with frontside 360
Slimchance = frontroll with frontside 360

The tantrum that was referred to up above is actually called a moby dick. I.e. A tantrum with a backside 360

I also found most of the guys here learn KGB's as their first kiting handlepass. Maybe its just a subjective issue, and different people prefer different things.

Here is a list of the tricks for those who are interested:

Trick Description
Bel Air to blind: Air Tantrum with a backside 180
Blind Pete: A toeside back roll with backside 360
Crow Mobe: A toeside front roll with frontside 360.
Crow Mobe 540: A toeside front roll with frontside 540
Dum Dum: A toeside front roll with backside 360
Dum Dum 540 A toeside front roll with backside 540
Fat Chance: A switchstance heelside front flip with a frontside 360
Flavour Flip: A toeside front flip with a backside 360
Fruit Loop: A toeside front flip with a backside 180
Half-Cab Double Back Roll Mobe: A Half-Cab Double back roll with an additional 180
Hasslehoff: A switch heelside front flip with a backside 180
KGB: A heelside backroll with a handle-pass backside 360
KGB 540: A heelside backroll with a wrapped backside 540
Mobius: A heelside Backroll with a frontside 360.
Mobe 540: A heelside Backroll with a frontside 540
Moby Dick: A tantrum with a backside 360
Orbital 540: An over the line, inverted, backside 540
Pete Rose: A toeside back roll with frontside 360. Typically done with a slob or method grab
Pete Rose 540: A toeside back roll with frontside 540
Roll to Blind: A heelside backroll with a backside 180
Skeezer: A switchstance toeside front roll with frontside 360. Another name for a switch Crow Mobe
Slim Chance: A heelside front flip with a frontside 360
Slim Chance 540: A heelside front flip with a frontside 540
Switch Front w/backside 360: A switchstance front flip with a backside 360
Tantrum to Blind: A tantrum with an indy grab and a backside 180
Toeside Roll to Blind (G-spot): A toeside back roll with a wrapped/handle-pass backside 180
Tootsie Roll: A toeside front roll with a backside 180
X-Mobe: A switch stance toeside backroll with a frontside 360. AKA switch Pete Rose