I think paladins should take 30 vit, and it isn't close. Especially single target, holding aggro is a joke. If you are having issues holding aggro, the small dps boost from 30 str won't save you. The mitigation it provides is also small, as at most, 30 str will only move you up one tier on the block/parry chart, giving another 1% on parries and shield blocks.

http://valk.dancing-mad.com/?page_id=227

More health, however, is always a good thing. Since paladins have lower health than wars, I think it is imperative that they get as much vit as they can from gear. Paladins have cd's for days, so there is less need to eke out a little more defense at the cost of health. From what little endgame content I've done (cleared hm ifrit, a few attempts on garuda, lvl 50 dungeons), bosses will hit hard enough for a high health buffer to be needed, especially on paladins who start with 25% less health than wars.