I've been using Lyft quite a bit this year, and I've asked every driver if they drive for both (yes) and which they prefer (Lyft, because it pays better). Anecdata, I know.
Also, I've observed anecdotally that the Lyft passengers are nicer. I've talked with various people about why that is and there are various theories, but generally the idea is that it starts at the top. Uber has a history of dick moves and I think that reflects in the different clientele.