rain garden ready for winter
From the plant’s perspective either is fine. For insects, birds and wildlife leaving the foliage until spring is best. Some experts say leaving the foliage up helps trap snow and moisture and that is beneficial. It is probably not so beneficial that if you really hate the ragged look cutting down the dead stems is ok. If you have serious problems with 4 lined plant bugs cutting down the foliage helps reduce numbers next year because their eggs overwinter in stems.