I wouldn't narrow "#1" down to only one, too many variables, & different needs for different situations. Rigel would be up there for the moderns, with Monteleone; I like Breedlove's mandos, & there are a bunch of highly respected small builders who are right up there, too, as well as Peter Langdell's former Rigel partner, Peter Mix with the carbon fiber New Mad's.
Looks like, aside from Gibson, probably the most popular mandolins (US made) are Collings & Weber. Possibly most lusted after, besides vintage Gibsons, are Gilchrist's(Aussie) & Dudenbostel.