I have recently been spending some time looking at the many drool-worthy bikes that are listed in the Eroica Register. All of these bikes were registered by their owners (there is a fee to have your bike registered) and were then "judged" as to their state and period correctness. The official listing can be reached here: http://www.eroica.it/elencobici.php
Bianchi and Legnano are obviously the most common given that they WERE the Italian bicycle rivalry for decades, especially the pre-1960 period that is celebrated by l'Eroica ride. Then followed by Colnagos (15 bikes, a number of which brought by foreigners), then another group of builders from the Heroic period prior to 1960 such as Atala (9 bikes), Frejus (8 bikes), Bartali (7 bikes), Ganna (7 bikes) and Wilier (7 bikes). All of the preceding are what one must consider to be products of large-scale industrial production. Some of you might want to exclude Colnago from the industrial production category, but in my eyes when you are producing more than 20K frames in one year, which Colnago hit in it best years, that is industrial production. It is after this group that you see some surprises and the appearance of the true boutique builders of the modern, post-eroica period makers. There are 6 Masi bikes (3 of which were brought over by Americans) 5 Marastoni bikes (out of a total production of perhaps 3-4000 bikes in 50 plus years of production!), 4 pre-Mexican production Benotto bikes, 4 Cinelli's, 4 Pinarello's (perhaps not fairly considered a boutique builder given their production totals), 4 Gavel bikes (I bet none of you have ever heard of them! They are a brand that is local to the ride area and are not normally considered collectible) 3 Patelli bikes (you don't hear his name mentioned much in the US), 3 Gios bikes and 2 De Rosa's. I believe the presence of the multiple Marastoni's, the early Benotto's and the Patelli's give a strong indication of how well they are respected in Italy, even if virtually unknown here in the US.
One of my favorites is this B.S.A.: http://www.eroica.it/documenti/0245%...0Girardini.pdf
Any others wanting to point out their favorites?