I'll throw out a vote for Deezer... It seems to work really well with building a music profile based on songs you like. Plus the Android Auto interface is (in my opinion) less stuttery than Spotify. But Spotify definitely has a bigger library and more exclusive stuff.
To play locally stored music I use Shuttle player. I came from Windows Phone so was at a total loss when coming over to my Razer Phone . Tried a lot of different apps and settled on shuttle which has worked out great.
I've been using Pulsar to play my local music on my RP2. I'll have to check out Shuttle and compare. I also have Spotify and as everyone knows, they don't carry everything, hence my need to want to store music locally on my device, at FLAC or 320kps quality.