Whole sign houses
The oldest house system: the rising sign becomes the whole first house, the next sign the second, and so on. Every house is exactly one sign. Simple, ancient, and back in wide use.
In whole sign houses, the sign rising at birth is the first house, all thirty degrees of it. The next sign is the second house, and so on around the wheel: houses and signs coincide completely. The Ascendant still matters, but it floats somewhere inside the first house instead of starting it.
This is the house system of Hellenistic astrology, the tradition's oldest layer, and its modern revival has made it Placidus's main rival. Its appeals are practical: no intermediate cusp mathematics, no distortion at high latitudes, and clean rules, since a planet changes house exactly when it changes sign.
The trade is that the Midheaven no longer marks the tenth house cusp; it falls where it falls, often in the ninth or eleventh. Whether that is a flaw or a feature is one of the friendlier debates in astrology. Compare your own chart both ways and notice what moves.