I think the only advantage, if that's the right word, to the vanguard is you can get the .257 or .300 weatherby calibers. I like the stock on the Howa better, it's cheaper, and exactly the same action. (Howa actually makes the weatherby vanguard line FYI.)
I got mine on a package deal with a nikko-sterling scope for $500. For a cheaper rifle, they're really pretty impressive. And the scope isn't bad. The only difference between vanguard and Howa is the stamp on the receiver. Howa comes with a pillar bedded hogue over mould stock.
I bought a weatherby vanguard .223 about a month ago. It wouldn't group 55 grain bullets very well. I went to 40 grain bullets and its awesome. So if you're going to need heavier bullets to disable your target, then you don't want the Weatherby with the 1:12 twist. You probably want a 1:8 or 1:9 twist to stabilize 55-80 grain bullets. The 40 grain bullets will blow a pumpkin up at 200 yards, but I don't know how much penetration you would get with larger game.