Best since 2005, at least, perhaps best of the modern era.
Obviously one of the Soviet teams of the early 80s would be the best WC team ever - this was back when the USSR could even beat Canada's A team.
So I guess it's between this one and the lockout-year Czech Republic team. They lost a game that year, but they had much tougher competition with everyone bringing their top players. They still managed an excellent goal differential (25 GF, 9 GA). Vokoun in net (who I'd actually take over Smith), their entire defence (except for Hejda, the 8th defenceman) was top-4 NHL defencemen, and a pretty deep forward group - Jagr was the only superstar, but they also had a bunch of second-tier stars like Hemsky, Prospal, and Straka.
Crosby+Giroux+Seguin still looks too good for me not to take 2015 Canada at least on paper, but if you throw the 2005 Czech team vs. 2015 Canada on the ice for a game, it could easily go either way.