I have owned 650 BSAs and Triumphs, many Honda twins, and have a Commando now. The Commando kills the other British cousins for raw power, but the oil-in-frame Triumph and BSA 650 twins are great, underrated bikes. They don't get the "classic" prices like pre-'71 bikes (especially the Bonneville), but handle great and are solid bikes in my opinion. The A65 engine has some oil pump issues, so I'd recommend the Triumph over the BSA, but either is great.
The XS650 is the only bike that is comparable, really. That's not to say the other Japanese twins aren't great, they're just very different with the 180° cranks. The CB/CL450 is a great bike, much more like the SOHC you're familiar with than a British twin.
If you want something modern that looks great (and better than the modern Bonnevilles), check out the 2000-01 Kawasaki W650. There weren't many in the US, but they are great bikes.