If you're looking for a proper
rain cape, Cleverhood makes some wonderful ones. Granted, they're more closely based on Dutch-style bike positioning (i.e. more upright), but they're well made, vent reasonably well, and are purpose-built for riding a bicycle in the rain.
Cleverhood also makes an
anorak that may work better for riders in more aggressive riding positions like MTBs, road, and gravel setups.
If you want a jersey that's great for precipitation (and don't want a flappy fabric tent around you), the classic
Castelli Gabba works well. It's fairly waterproof yet still quite breathable. This item is sought out by pro racers for the cold "classics racing period" in the spring in Belgium and The Netherlands.
Rapha's rain jackets are fantastic, if pricey. Their
Pro Team Lightweight Gore-Text Jacket is simply amazing: light, not too flappy, keeps you dry
and breathes well. But it's nearly $300, so it's not everyone's cuppa. Their
Core Rain Jacket II or
Commuter Jacket are more affordable options.
And yes, Showers Pass makes awesome rainwear that's super waterproof. But as
@cantunamunch says: they're not very breathable and turn into sauna suits if you work up a sweat.
And cutting to the chase: fenders help a lot! I use SKS RaceBlade Pro removable fenders on my Moots and they provide excellent splash protection on wet roads. Don't discount fenders! In combination with a lighter, more breathable jacket they work a charm.