What valve would be the best for a model rocket with a hybrid engine?
It depends on a lot of factors.
Most valves with the specs you need will work really, but you'll have to carefully determine your specs. There's not really a single answer.
What kind of thrust are you designing your engine for? This (amongst other things) will determine your minimum needed flow rate, and will determine the pressures this valve will need to be able to cope with. These things will be the most important valve specs you'll be considering.
I don't know where exactly your valve will be in your engine, but make sure it can withstand the heat its exposed to.
On the flipside, knowing you'll be using GOX, you'll probably just use the pressure from your oxygen tank to power your engine. As the oxygen will be expanding, the MOV might tend to freeze up and lock itself in place. Beware of that as well when choosing a valve.
Not all valves will be able to safely operate in a pure oxygen environment. However, as we're talking model rockets here (the operating time of your engine is quite short I suppose) it'd surprise me if that would turn out to be an issue.
To end with, although maybe not directly related to your question about the valve, make sure you understand hybrid engine throttling. It can get more complicated than you might anticipate.