I used a set of Hammonds on my 18 watt. No complaints at all, though I have yet to love them as much as the Classic Tone in all of my other builds. I've toyed with rebuilding my Matamp using Mercury metal but the sticker shock is a bit astounding.Where is a good place to get transformers now? Triad looks about done, and what I do see, the pricing has gone up a lot since I was working on amps.
Mojotone is a good place to grab Heyboer iron when in stock. For Fender style builds I believe Bryan Sour from Sour Amps is making some nice boutique iron though he may just be doing OTs at this point.
Losing Classic Tone has been a giant bummer.