Best 1x12 british type speaker?

Playing through a Suhr PT100se. Fender cleans and Marshall type overdrive. Want something with a nice low end, low midrange response.

Hummm ... that's a super-cool and rare amp!  Problem is, it's 100watts ... so that starts limiting choices.

In 9 outta 10 cases, I's say go ET65 or ReaperHP ... but In your case, I'm going to say go with the Blackhawk HP ... a PERFECT match to that ultra elegant amp!

The other VERY good choice would be an ET90 ... as long as you don't push the amp to it's ultimate volume often.