Migrating Mac to Mac via iCloud
Although you can get whatever you can on your iPad via iCloud also on your new Mac via iCloud, you can not completely migrate Mac to Mac via iCloud. But, note that, this is actually (via iCloud) how I migrated to my new MBP last year as I preferred to have it set up fresh and I don't have too much data (just a few GB) outside pictures and music.

Even if you enable every iCloud category in System Preferences > iCloud, iCloud only synchs your user data files such as office documents, pdf files as well as pictures, contacts, calendars, etc. 

Unless you are subscribed to Apple Music or iTunes Match or they reside as regular files under the Documents folder, you won't have access to your music via only iCloud. iCloud will neither install the applications you have on your previous Mac onto the new one nor customize them or your system settings the way they are on your previous Mac. However, you can download the applications you have obtained from App Store with your previous Mac by signing in with the same Apple ID in your new Mac from App Store again. 

Apple recommends that you migrate from one Mac to another using Migration Assistant if you wish to do it as completely as possible.