Well asked! I've been trying to understand why I do.
I think it comes to this: Good places to live come from encouraging and empowering people to make those places their own, as communities.
What it means to be a democrat or a republican changes from place and decade to decade. What is effective in actualizing that community participation then also changes as a place changes over time (ironically, that's also why it's important to have that community participation).
AFAIK, the Republican party _used_ to stand for small, decentralized government; now they stand for ineffective and centralized government (despite the talking points).
I'm less clear on what the Democrats "used to be" (except racist, way back in the day), except that in this era and in these places, community participation is hampered by unaffordable housing, unaffordable and/or inaccessible healthcare, and a lack of living wages.
I know I haven't fully answered your question, but I've been at this for far too long. Thanks for asking so effectively!