Musicpi and mopidy, which one to choose?

So I am new to musicbox and I really like it so far. So I have been a huge spotify fan from the beginning and I love to listen to music. Lately I have gotton into home automation as well, where I have amazon Alexa ( Voice commands) to control my home. So here it goes what I would like to achieve.

I want to tell alexa “trigger playlist Rock” and then she will start that playlist on spotify. So to do this I need to be able to run a command line command to start that playlist. What is the command for that? Or the best is if I could use the mpd binding for openhab, however it seems like it does not support playlist commands.

Then what will be really smooth, would be if I could use alexa to search for artist and find it on spotify, but I have no Idea how to achieve this:)

My final question, whats the benefit of the music pi GUI over spotify GUI? Well to put it short if I can not get alexa to search for artist I could just use mopidy(command line tool or?) to play playlist and then use spotify and chromecat/chrome audio (as I do today) if I first need to start up my phone/laptop to search for artist? Does the musicbox has some cool features that spotify does not have? Something I am missing?

And thoughts on setup would be highly appreciated.

Can you use MPC? For IR control I use mpc load “Your Playlist Name Here”;mpc shuffle;mpc play
There is a search facility but I’ve never tried it.
More on MPC here

There might be some useful information on Steven Hicksons Voice Command site

Be interested to hear how you get on with voice commands.