Realize there are many divergent opinions here.
Advantages of jet:
Safer - no one will ever get cut on your prop
Shallower water capability - the jet is actually slightly higher than the boat bottom, so you don't have the lower unit, prop, and skeg deeper than the hull. On the other hand, you *really* need to watch it so you don't suck sand into your jet.
Handling - at planing speed, handling far surpasses a prop IMHO
Fun - (highly subjective rating here)
Maintenance - winterizing is usually much easier
Advantages of conventional:
Option of outboard, I/O, inboard. Outboards are much easier to work on. You can also change props, optimizing for speed, hole shot, etc...
Much greater efficiency, both HP and miles (hours) per gallon of fuel
Hole Shot performance - slightly better due to greater efficiency
Handling - at no-wake, a jet is difficult to handle; it's directional control is by the direction of the jet, so if there's not much power, there's not much control.
Long-term maintenance - eventually will need to replace impeller and wear ring.
As for overall speed, that depends on many factors. Generally, due to greater efficiency, a prop might be faster than a jet, other factors being equal.
Also consider what-ifs. A few times when we've been on a lake with more weeds (Eurasian milfoil has invaded the Midwest), I've had weeds mat the intake grate on the bottom. Restricted water intake = no jet power. On a prop, you'd most likely gently put it in reverse a bit, and the prop would free itself from the weeds. Some jets (I've heard) have a way to free weeds from the intake grate. Mine, I've had to shut off the engine, swim under the boat and pull 'em out and off by hand. This has encouraged us to not go into some coves or other areas where there's lots of weeds. Of course, our boat is older and entry-level, so newer / better jets may have that problem addressed. Or it may not be an issue in the waters where you are.
All told, it sounds like my comparisons lean toward props. But for the lake where our cottage is, the jet had definite advantages -- especially in shallow water.
You might also browse the forums at jetboating.net -- of course, everyone there is just a little biased that way.
HTH
Al