EKG is a great hop and as traditional as it gets. I’ve also had good luck with First Gold, and am experimenting with Northdown and Phoenix although I don’t have results on those yet.
I’ve been leaning into Bitters myself and appreciate the flavors of Willammette in a bitter or mild. I also bought but haven’t used Sonnett Goldings reading that they’re a product of EKG?? but not a bunch of information exists on that. Their aroma is mild and pleasing.
You might find some helpful info with a couple of Ken Lenard’s recipes at his personal site. Muddy, I hope this turns into a good thread along the way. I’m really digging bitters and look for great feedback.
If you’re looking for something way out there, then you could look into Caliente. I recently brewed a single-hop batch with this and the flavor profile was very similar to Fuggles, but with some lemon and peach notes. Aroma-wise, it is a fruit-bomb with a fresh peach/plum aroma, so it would be out of style as a late or dry-hop addition for a lot of English beers. But I bet it would really nice as an addition in the 30-15 minute range for an English IPA or maybe even an ESB.