I’m looking for a jacket that is…
Waterproof
Goretex or just as breathable With thumb loops (the most important criteria)
Slim cut with a drop back
this is not really true – goretex is not breathable, or at least it doesn’t breathe as quickly as you can produce sweat when working hard so it becomes as wet inside as it is outside (assuming its raining).
If you’re not working hard then goretex will do.
I’ve just started using neoshell and it is by a long margin the best breathable waterproof I’ve ever used. Trouble is there aren’t that many jackets available in the new fabric.
Sugoi does a bike specific one, but there has been criticism of its cut.
Rab does a neo stretch jacket which is too bulky (in my opinion), they do a new lighter one called the Myriad, which might be good but I haven’t tried it (I don’t get on with the rab hood).
I’ve got a marmot zion jacket that is best suited for the winter, so trying to get the marmot nabu which is supposed to be lighter.
Montane have released the further faster jacket, which is built from neoshell and is specifically designed for fast moving activities, such as mountain marathons or trail running, but not sure whether the cut would suit biking.