Parse vs. Firebase for user accounts

We are looking to add a backend to our app that basically allows us to sync user data across multiple devices.

Structure of our data mainly consists of user accounts with 3 “collections” or types of data to be stored.

– Past Activities (currently Web SQL tracking id, date, type of activity, length of activity) (between 10-80 rows/entries per user)
– Settings (simple object with user settings as key value pairs, currently with localForage)
– Custom Activities (simple array with maybe 5 objects max)

I have been looking at Firebase and Parse to decide which would give us best control of these three types of collections that are associated directly to the user. Out of the box support of this is top priority in choosing, followed by simplicity and finally price. Expecting about 500 concurrent users at all time but only really making requests 2-5 times per a 10 minute session.

Anyone had a similar experience?

Hardest information for me to find is whether Parse allows multiple collections to be associated to individual users rather than what they always seem to describe as a main collection with multiple users reading and writing the same Class/Collection.

It appears as if this is very easy to structure within Firebase, but we don’t really need a massive amount of real time data and syncing which appears to be their strongest feature.