Portugal is the opposite of Burgundy: if you’re really knowledgeable, and you know where to look, you might just find bad deals and poor QPR.
As a Portuguese I find it hard to comment on this thread from a US based perspective, since i’m not exactly sure what goes abroad. I would second all the recommendations that have been made so far and add a few more off the top of my head:
Herdade do Mouchão’s wines are probably the only ones that have seamlessly bridged the gap between ‘traditional’ winemaking (which in Portugal of the old days meant earthy, highly extracted and in need of long cellaring) and the modern paradigm. Their cellar and winemaking practices remain relatively un-technological. These are gravel soils similar to those in many left bank Bordeaux proprieties, and mostly planted to a grape variety that always played second fiddle in its native France, but arguably has reached its greatest heights in the Alentejo: Alicante Bouschet. Part of the house style is the use of macacauba wood, which has a different flavor profile from both French and American oak.
I have always loved the wines from Tapada de Coelheiros, which are still drinking fantastically down to the very first vintage (1991). They are unquestionably part of a trend, now out of fashion, for Portuguese winemakers to plant French grape varieties as part of modernization efforts. These wines blend cab sauv with Alentejo grapes like Trincadeira and Aragonês, and drink a lot like Bordeaux’s Iberian cousins. I doubt any of the old releases are available in the US, but the newer ones might be.
Rita Marques’ Conceito wines strike that balance between elegant drinkability and Douro character for me. Sort of venn diagram wines between hedonists and lovers of restraint, in my view, with their satin-y textures that are luscious yet ‘feminine’.
I don’t believe my friendship with Carlos Lucas makes me biased towards his wines from Quinta do Ribeiro Santo (Dão). These are relatively large production but consistently chiseled and refined across the entirety of the price range and portfolio. He’s mostly known for his whites, but the red Grande Reserva is beautiful: perfumed, savory, very ‘old world’. Some of his other top reds are a bit bulkier.
You can safely buy anything out of Taboadella, Luísa Amorim’s megaproject in the Dão. The facilities are top notch, the investment is grandiose, and the winemaker is the brilliant Jorge Alves, the man who is also responsible for the Quanta Terra project (excellent Douro wines, though on the burly side) and Luísa Amorim’s remaining projects (Quinta Nova in the Douro, and Herdade Aldeia de Cima in the Alentejo). The reason I single out Taboadella is that I love the Dão, and I can sense from the wines that Jorge (who is very much a Douro local) loves it too.
Posters above have already mentioned a number of excellent Bairrada producers, but I’d like to add Quinta das Bágeiras and Kompassus. Bágeiras’ Mário Sérgio is a champagne nut whose bubbles are the closest to a champagne doppelganger that Bairrada espumante can get, but his reds are all Baga character, just the way we like it: crunchy, earthy, with modest ABV. You could lay down his red Reserva for less than 10€ a bottle. As for Kompassus, the wines are made by Anselmo Mendes, so 'nuff said.
Others have already mentioned Quinta da Gaivosa, from veteran winemaker Domingos Alves de Sousa. While Abandonado, Vinha do Lordelo and Reserva Pessoal are big and mean, the base Quinta da Gaivosa is consistently more elegant. 2017 is smokin’, but already running out even over here. The other great producer in the Baixo Corgo subregion of the Douro would be Quinta do Côtto. I’m partial to their Vinha do Dote bottling, which is a beautiful expression of the more humid, cooler climate of that specific parcel/terroir, fine to either drink now or age for a decade or two and carrying a very modest price tag.
The Beira Interior is the up and coming region around here, and the producers to look out for would be Quinta da Biaia (from the hugely talented young winemaker Luis Leocádio) and Quinta dos Termos (from the veteran Virgílio Loureiro). Biaia has very high altitude vineyards resulting in wines that are remarkably fresh, firm and structured. The 2017 Reserva is another bottle you can grab for less than 20€ that will go twenty years: everything is amped up in a way that is decidedly serious and has little sexiness to it. Quinta dos Termos’ wines are perhaps more consensual, but impeccably balanced.
I have managed to completely skip the Tejo and Lisbon regions, which is a huge deficit on my part! Their wines are better than ever and I need to dig deeper into them outside the very well known producers. It might not look like it, but there is a lot more wine being made in Portugal than I’m aware of…