I agree with most of the above comments, I would want a dog 80 to 110 lbs with good leg that is fast an a good vest they can move in. if it's open country an u can get to them fast a short range hard as nails dogs is good, but if your dog was going to hunt out far or in thicker country I would like them to be hard but smart so if u got onto a bad boar an u couldn't get to them quick they would let got an bay alittle till u got their an then they would catch again. Coz even if they hold smart if u get on a bad boar one out in a tank or really thick stuff where they can't move or u cant get to them they will get hurt eventually. In my experience hunting back in Australia I've had more luck with a dog that would let go then catch when u got their then a hang till u die type of dog ( I think it's smart) some people don't like it an think they will get u hurt, but the best dog I had was this type of dog I never seen him bay a pig but heard him many times an I caught plenty of pigs over 200lb just with him.
I also ran a hard as nails type dog which was great if u got to her quick but many times when I eventually found her she was over heated or cut down ( before I had trackers) an the other dog would get the job done.
Over hear I started out running a Dane/pit which is a hard hang till u die type dog (no bay) with one lose cur that wouldn't help catch an I caught some good boars with just him catching but also got him cut down a bit as he would go as far as the cur would, now I run another rcd with him which is by him out of a Dogo/ridgeback gyp an it's made life alot easyer on him making it easyer to control a good pig.
Ive hunted theis to rcds together on small places, an feedlots with no curs an had good luck with it, it's a fun way to Hunt if u have the right situation to do it. Just my thoughts Hugh