I'm not familiar with either rockhoster.com or planethoster.com, as they don't appear to be well-established or well-known web hosting companies. However, in general, when comparing web hosting services, it's important to consider factors such as the types of hosting plans they offer, their uptime guarantees, the features they provide (such as the number of websites and email accounts you can have), the amount of storage and bandwidth they offer, the level of customer support they provide, and their pricing.
Additionally it's important to look at their reputation and reviews as well.
It would be advisable to check the customer review and rating for each of the service providers. Some websites like trustpilot, sitejabber are considered good places to check the reviews.
I would recommend doing some research to see if either of these companies have a good reputation and if they meet your specific hosting needs.
If you are not sure which one to choose , you can also look for other providers like GoDaddy, Bluehost, HostGator, etc and compare their service and pricing.