I've always considered JetBlue to be a value leader vs. low cost leader. They have nicer seats, in seat entertainment in all classes and have a pricing/refund/exchange policy that is more customer friendly than competitors. Spirit is just going for low cost. Southwest is in between where they want low cost but you have to fight for a seat and might needs to have 2 or 3 stops to cross the country depending on where you start.

I assume you're talking about JetBlue's Mint product which is all business class for some cross country flights and a few international. Again, I think they are trying to provide the best value for business class compared to the larger carriers.