I think Sartorial is the best thing they've done in years. A modern take on the classic fougere (think Brut). A great gentlemanly scent. it has a foot in the trad world, and a foot in the contemporary world. Has garnered a lot of praise in the Basenotes community and is a personal favorite of mine when suiting up. Great scent; great longevity.
English Fern is a wet shaver classic and you can't go wrong with it. For me, it's personality is a bit more spring and summer; casual.
Put me in the "loathe" column for Blenheim Bouquet which a lot of people will suggest. Lemon and pine. Lasts mere minutes on me. It is a wet shaver favorite and I don't believe my opinion is THE opinion. But if longevity is a concern, make sure you read reviews on it. Lots of issues with longevity. That being said, nose sensitivity varies and you might find it lasts all day.
I like a lot of Pen's scents. Hamman Bouquet and Blenheim Bouquet are both classics and favorites of mine. Opus 1870 and, particularly Sartorial are scents that bridge traditional and modern. Castile is a nice soapy orange that feels like you've just left the shower. Raquets is a great take on the classic Clubman style barbershop scent Almost everything I've sampled from them is, at the least, pleasant and wearable.
But if you made me pick one, hands down it's English Fern: classic, great longevity, very British.
(Or maybe I'd cheat and get Trumper's Wild Fern and get a bottle of Hamman Bouquet ;-))
I believe I have only tried their English Fern and Blenheim Bouquet. While Blenheim Bouquet is certainly a nice frag, their are others in it's genre I prefer. English Fern on the other hand is a solid member of my Top Ten.