Best Malz Vienna is the one available at my usual online supplier so I will probably go that way. I have heard that MFB's Vienna is pretty tame and that their "Special Aromatic" (5L) is more vienna-like. No experience.
True. Avangard Pils is a European malt and I have gone through a couple of sacks of it with good results. I'm not sure that I would say that the Avangard beers were better than say Best malz or even the Weyermann pils (regular, floor-malted, Barke) batches and I even have some Belgian Pils batches in there too but I keep changing things, tweaking things and adding things (brewtan) so it's tough to compare.
Re-reading the OP... I'm not sure that you're going to get "toasty" notes from 100% Vienna. You will get good, deep character with a good amount of breadiness and maltiness, for sure but not sure on the toasty thing. Maybe someone else could chime in on that part.
So I dug into a couple books on hand.
Randy Mosher says of Vienna "A clean caramelly character without toastiness" "Use: Basemalt when a caramel character without a toasty edge is desired.
About Vienna, Mallett says in Malt "The flavor is slightly toasty, slightly nutty, and pairs well with spicy, noble hops." He also says of biscuit malt "The flavors share some characteristics with Vienna malt but are much more intense."
So it seems it may really depend on who's tasting it and probably even more on which maltster produced it. I going to have try this out for my self. I'll probably start with a 100% vienna lager, maybe something "SMaSH-ish" along the lines of what Drez suggested.