This is the fundamental of all electric guitar sounds, James: gain structure. And you’re right, different pedals sound radically different with different amps. But don’t despair…
Gain, compression and EQ: a Tube Screamer works so well with a blackface Fender because it offers the amp a bit of compression, a kick in mids and enough gain and level to take all that sparkly clean stuff into nice overdrive. By contrast, both your amps have a lot of available gain, quite a bit of compression in the front-end and a totally different EQ character.
We’d be looking at a full-range boost that can boost clean sounds, and/or drive the amp’s OD into sweeter drive and compression without overly colouring the sound. Having some bass attenuation will help with clarity. Fuzz-wise, the world is your oyster. Marshall and Orange amps tend to like fuzz because you can have the front-end of the amp breaking up slightly. Fuzz Face, Big Muff, Tone Bender, Power Driver… all sounds that you should experiment with. As for ODs, there are just so many. Avoid a big mid hump, we’d say, and go for something with plenty of sizzle if you’re playing in a rock style. You may not even need an OD with the right boost and fuzz combination. 02
If it’s a germanium fuzz, run that first. Then you can use the boost to boost it louder. If the fuzz plays nicely after the boost, try that, too, for some wild compression and gain. As for boost and OD, running boost first will push the OD into much heavier saturation; running it after will give you a level lift after the OD… but only if your amp is set relatively clean. If the amp is set dirty, you’ll just get more gain and compression. In that case, try the boost in the loop. Good luck!