Right now? Both are looking at UFA status, or priority UFA at best.
If we compare current abilities, there's no question that Ian Book has a better chance of making a pro team.
Jalen Hurts is by far the superior athlete, but, at this time, is lacking when it comes to the abilities that the pro teams want in a quarterback.
A NFL quarterback needs to show the following:
1) Accuracy: By far and away, the most important aspect. Obviously, if you miss your targets badly, then the offense will stall. If you don't deliver an accurate ball and your receivers need to reach out for them, you're going to get them killed.
2) Timing: Hitting receivers in stride is what allows most pro style offenses to open up the rest of the game.
3) Go through multiple receiver progression, and be able to read and recognize the open receiver quickly. While a college QB can get away with only looking at WR1 and WR2 before scrambling, that kind of play will get you clobbered in the NFL, where those front seven defenders are a hell of a lot faster and stronger.
4) Arm strength: Important that you be able to stretch the field vertically to a reasonable degree
5) Pass protection recognition: Needs to be able to make pass protection audibles on the fly. Defenses in the NFL are very complex, and well-disguised. Often times, they'll shift, and a QB needs to make the audible.
Being able to scramble or make designed QB runs are simply icing on the cake.
In all of those five critical areas, Ian Book has a significant advantage over Jalen Hurts. The only one that Hurts has an advantage over Book, is pure arm strength. Unfortunately, the CFL and AFL are quite well-stocked with strong-armed QB's who didn't have the accuracy and precision needed.
At this time, Book would have the better chance of making a NFL roster as a backup QB. Hurts wouldn't make it even as a backup.
If Jalen Hurts can show that he has improved in the other 4 areas while playing at Oklahoma (and they are quite pass-happy), then I think he would become draftable.
If Ian Book can show improved arm strength, then he could also become draftable.