which nozzle is best for my material?

Water Jet Nozzle:

Soft rubber
Foam
Extremely thin stuff like Foil
Carpet
Paper and cardboard
Soft Gasket material
Candy bars
Diapers
Soft, or thin wood
...All sorts of other soft stuff

AbrasiveJet Nozzle:

Hardened tool steel
Titanium
Aluminum
Hard Rubber
Stone
Inconel
Hastalloy
Copper
Exotic materials
Hard, or thick Wood
Glass (even bullet proof!)
Marble
Plastic
Nylon
Graphite
Many ceramics
Carbon Fiber
Composites
mild steel
Stainless Steel
Kevlar
Granite
Mixed materials
Brass
In Fact, there are very few materials that abrasivejets can't cut!