Dual Class Combos

I've been in a campaign that uses the dual class variant rules for a while now, and it's gotten me wondering if any of the particular class combos we ended up with were anything notorious as an insane combo or anything. I assume something like Fighter + any other martial would break immediately, with the boosted weapon proficiency, but what are some other combos that tend to break way ahead of other combos?

Our current party is:
- Champion/Sorcerer (Redemption/Angelic)
- Swashbuckler/Sorcerer (Wit/Undead)
- Ranger/Monk (Flurry/–)
- Wizard/Witch (Boundary+Familiar/Inscribed)
- Psychic/Bard (Distant+Emotion/Maestro)

As a side note, I only just now noticed how Monk is, like, the only class that doesn't really have a major branch, like the ones I denoted for every other class