Many growers have success with Cattleya walkeriana but the flowers would always fail to mature on the two plants I had. After several years I finally gave up on them. Cattleya violacea is also very tricky to bloom. I would also stay away from Cattleya amethystoglossa which needs to get quite large before it will bloom and the blooms don't last very long. Cattleya intermedia, Cattleya loddigesii, Cattleya jenmanii, Cattleya percivaliana and Cattleya maxima have all been easy for me to grow. Cattleya lueddemanniana, Cattleya trianae and Cattleya mossiae have beautiful traditional type blooms but I've never grown any of them. I don't think they're difficult though. Good luck with choosing just one.