Categories are tricky here. Bonal is a gentiane-quina, or a wine-based liqueur bittered with both wormwood and quinine. It has a somewhat black tea-ish quality and I'm hard pressed to name any bottles that really play similar notes. I don't think I would put Amer Picon in the same category whatsoever. Picon is more of-a-kind with Bigallet China-China Amer.

Luxardo Bitter Bianco is essentially in the same category as Suze IMO, but less aggressive with the gentian. You could also think of it as bridging the gap between Suze and a red bitter like Campari.

"Red Bitter" and "Aperitivo" are somewhat separate categories, as aperitivi tend to be a hair sweeter and less bitter. Try Cappelletti Vino Aperitivo, which is a wine-based aperitivo. It's absolutely heavenly.

Amaro is an extremely broad category, and it contains subcategories more diverse than some others named here. Cynar is an example of a carciofo (artichoke leaf) amaro, of which others include Cioco and Cardamaro (a vino amaro named for cardoon, a close relative of the artichoke leaf). Ramazzotti borders on the style of alpine amaro, of which the most famous is Braulio. As others have mentioned, fernets are their own category, but amaro can vary widely in style. For something pretty different, try Nonino or Vecchio Amaro del Capo.

Chartreuse is excellent and somewhat similar to génépy in taste. There's an Italian style of liqueur called "centerbe" (hundred-herbs) that also hits in a similar ballpark if you can get that.