Stranded is a pain to work with so I would avoid it. From the specs you are only suppose to use stranded cable for patch cables between the end equipment and the wall jacks. The standard says you have to use solid in the walls. Now I strongly suspect stranded would actually work in the walls even though it is not a certified installation. Still there is little reason to do it, solid wire is much cheaper and it has more than enough flexibility to easily get it installed in walls.
Be very careful to buy 100% copper cable, there is lots of crappy CCA cable being sold by many vendors lately. That cable is not certified and is very difficult to get terminated correctly, over time the aluminum expands and contracts different enough...