Consignment is safest for you, but risky for the gallery - I'm surprised they'll offer that to artists they've never worked with before.
The booth rental is a reasonable arrangement. You're just up in Johnson City, right? Booth rentals at places like Kress and Woolworth Walk in downtown Asheville are significantly higher. So depending on where the gallery is, and the amount of foot traffic you can expect, that's not a terrible deal. You may want to start on consignment and then switch over after a year or so if the consignment is working well. For a reasonable amount of space, the two would about equalize in terms of commission, and you may be able to get a lease-like agreement that would give you some security about staying there. Can you customize your space? Signage, paint, that kind of thing?
Wholesale can be nice for a gallery that moves artwork, but you have to be ok with; a) making wholesale, and b) not choosing which of your pieces hang and where/how they are hung. Presentation is huge, don't give that away too easily.
What will they do for you? Do they advertise in local media? Are they active online? Do they have a good website? Mailing list? Events? Ask them about all of that, you want your commission to be partly working to support the space and the staff, but also working towards promotion to get people in to see your artwork.
Good luck! I've been in galleries in the area for going on 12 years now, I'm happy to share with you whatever you think would be helpful. :)
PS. I just started in a new gallery in Kingsport. We should get lunch sometime!