If you're going to have a public subsidy to education, vouchers are clearly a better way of delivering it. They should result in some loosening up and privatization of the government school system.
I think we spend too much on K-12 education a.k.a. teachers' salaries. It's the only industry where you never see any productivity increases.
The problem with K-12 education is socialism and the solution is capitalism.
There's no particular relationship between spending and educational results. Most education spending is actually on salaries, and that's allocated according to political muscle.