I can't say it was the library that sold me on pre-ordering the PS4; it was the moment SCE announced the price and Amazon took pre-orders that I placed mine, knowing full well that the same franchises (in particular the SCE exclusives) I enjoyed on the PS3 would be continued on the PS4 in addition to healthy 3rd party support.
If I was buying one today based upon the library, since the only remaining Nintendo IPs I still follow are Metroid and Zelda, I'd still be picking the PS4 on the basis of 3rd party support, superior performance of multi platform titles with added incentive from Infamous (not a system seller for me, but still a franchise among favorites).
But future titles rather than current releases, since we're supposed to be looking at Meta scores, would matter more to me, and since we don't have scores for that which has not been released, I'd have to say that the Meta score average wouldn't make any difference in my decision.