See the UCSC docs https://genome.ucsc.edu/goldenpath/help/hgTrackHubHelp.html#Hosting
One free option, at reduced speed, is Cyverse. Two other free options, with higher speed but limited file sizes, are Figshare and Github.
As for the paid options, the UCSC page says this:
In general, commercial online cloud backup providers that charge a flat rate, like Dropbox, iCloud, Google Drive, Box.com, Microsoft OneDrive, Tencent Weiyun, Yandex.Disk, etc. do not work reliably as their business model requires rare and rate-limited data access, which is too slow or too limited for genome annotation display. However, commercial cloud storage offers that charge per GB transferred, like Amazon S3, Microsoft Azure Storage, Google Cloud Storage, Backblaze, Alibaba Object Store, etc. typically do work. For optimal performance, select a San Francisco / San Jose data center for the main UCSC site genome.ucsc.edu, a Frankfurt/Germany data center for genome-euro.ucsc.edu and a Tokyo data center for genome-asia.ucsc.edu.
Also, you can send email to the public mailing list at UCSC and ask us, as you did here.
Thank you. Yes, the answer from UCSC folks was :
"There are a few different public options you can use to host your big* data. A number of our users utilize CyVerse (http://www.cyverse.org/), but I encourage you to look at our FAQ page on the topic and explore all the options (https://genome.ucsc.edu/goldenpath/help/hgTrackHubHelp.html#Hosting).
Another option is to run a local copy of the Genome Browser on a virtual machine, which allows you to view big* files directly from your computer. If this seems like a valid solution, I would recommend you look at our GBiB documentation (https://genome.ucsc.edu/goldenpath/help/gbib.html#What). There is a specific section on that page that covers viewing your own data on the GBiB including big* files (https://genome.ucsc.edu/goldenpath/help/gbib.html#YourTracks)."