Most of these offer a basic service for free, which then at larger data demands morphs into a paid service.
The best known are probably Dropbox and Google.
Both these at one stage or another reduced the free space offered.
I find Google in general a confusing collection of services with hard to find preference settings and cluttered control panels. Perhaps that is just me.
I have used Mega for some time and at 50 GB storage for free, it is the best in terms of space. It does have a bandwidth restriction of 10 GB/month. It is a winner in terms of simplicity, clear instructions, speed and uncluttered outlay