Which (affordable-ish) front hubs are adaptable between QR and bolt through, I know of Pro II's but are any others worth considering.

Seems like most 140mm-ish forks are going bolt through these days so may need to get a new wheel for a forthcoming build on which I plan to use 130-150 forks….

Hope all they way. Practically infinately adaptable and quicker to do and cheaper than any other hub I am aware of that will allow you the same options. Plus – buying British will give you that lovely warm feeling inside!

Yeah, I have some plenty years old Hope XCs and they've never needed anymore than an oily rag waved in their general direction to keep them running, so am convinced of their quality (sorry PP) 🙂

When I looked into this a year and a bit ago hope were the only ones…

Nuke Proof Generator though I don't think they will do 15mm only QR or 20mm.

keppoch

Stans ZTR hubs are – the ones JRA are now selling.

You could also look at Halo spin doctors and DMR revolvers – both on CRC. Never used Halo's but I've had revolvers before and they were fine. Not sure that either of these are set up for use with 15mm bolt through forks though.