Fountain Pens

Seconding Aurora Borealis which has some great shading. Almost always have it inked up in a broader nib or stub.

If you like the Iroshizuku inks that you have, I also like Ku-Jaku, which is maybe on the bluer side of Syo-Ro.

If you want a different brand, I have really liked many of the Robert Oster inks, and they make a very nice looking teal with good shading called Deep Sea.

When in doubt, you could always order some samples and try them out! I personally usually get samples from Goulet, but there are other options too. For Diamine inks, cultpens periodically has good sales (both are UK based so usually much cheaper than US retailers anyway if you're in the USA) and it can be pretty affordable to pick up a bunch of smaller (30mL) bottles to try out while only paying one shipping fee.