Hostwinds is decent from what I’ve seen, especially for VPS and smaller reseller setups, but support experiences seem a bit mixed depending on the server/location. You could also look at A2 Hosting, KnownHost, VeeroTech, MechanicWeb, and InterServer reseller hosting because they’re mentioned pretty often in hosting communities.

InterServer Reseller Hosting is worth checking too if you want something affordable with WHM/cPanel and decent flexibility for the price.