Never really considered Barnes as a bowler who could be classified, personally. He wasn't pure spinner, and he certainly wasn't seamer. I'd never include him in a list of either spinners or seamers, though I consider him better than any of either of them.
As regards the best spinners, it's so ridiculous the way some people state out-of-hand that Warne is the greatest conventional Leg-Break-stock-ball wristspinner (ie, excluding Muralitharan who is a unique one-off and incomparable to any other wristspinner). He might be, sure, but there's no way he's unequivocally greater than either O'Reilly or Grimmett. Maybe in 10 years' time when the Warne-o-mania has faded more people will start to offer a fairer assessment.
As SJS mentioned, too, other fine wristspin bowlers included Benaud and Gupte (the most often criminally forgotten). But Abdul Qadir was in many ways a wasted talent.
Kumble - and, so I hear in recent times (would be interested to hear SJS's words on this as he'll have seen both bowl plenty), Chandrasekhar too - are somewhat different to the "normal" wristspin in that neither were prodigious spinners of the ball. They weren't fingerspinners but they were more like fingerspin than wristspin in one respect. This means I don't rank either up with the Grimmetts, O'Reillys and Warnes, or even Benauds or Guptes, but of course both were excellent bowlers.