Hi & first nas some basic questions about cloud

Hi, let me introduce myself
I'm Lucas and I'm from Austria.
Yesterday I installed OMV on the hp gen8 cube. So far so good.
Now I won't to install a cloud solution, specially because it makes it easier to access the files to my girlfriend (over the internet)
Or is there any other way?
I'm reading a lot about clouds, so my question is which one is the best owncloud, nextcloud or is there any better supplier?
Thanks a lot