The ASRock X870E Taichi wins in 10 out of 13 comparable specs, with 2 ties. Its biggest advantage is VRM Phases (200% better).
B660M DS3H DDR4 wins in 1 spec (MSRP: 82% better).
Recommendation
Choose X870E Taichi if you want the best overall performance — especially vrm phases.
Choose B660M DS3H DDR4 if msrp matters more to you.