If you are not already comfortable with both, pick whichever one you are comfortable with unless you're really interested in learning one of these.

I'd say it depends really on what you're trying to learn with this project. If you're only interested in making the bot for the sake of that experience alone, I would honestly recommend using jQuery because I feel like it would probably be less fuss to set up.

That being said, you can easily pace yourself and learn both (at least the basics) React and this Botkit SDK within the month if you have the discipline to do it.