Take this with a large grain of salt since I have no reason to believe either of these building were constructed any better than your typical new build, (which they both are) but I’ve been in both Hecht Warehouse (in Ivy City) and Ava H St (…near H St) and never heard any evidence of neighbors besides the occasional person passing outside my door, despite both being quite pet-friendly. Out of curiosity I just did a quick search of Google reviews and both buildings’ 100+ reviews are devoid of any mention of “noise” or “loud,” though there are probably other valid complaints I didn’t bother to search for.

I would avoid a townhouse. Given your budget I doubt you’ll rent the whole thing, and even though sound insulation between horizontal neighbors seems to be near 100% (at least in the historic DC-area buildings), none seem to have ironclad sound insulation separating higher and lower units. I’ve lived in a few of these historic townhouses as well and while I’ve been impressed by how well some are insulated, even the most considerate upstairs/downstairs neighbors aren’t totally silent.