Depend on the service you are using for massplanner
Twitter for example, is not very strict about proxies, so just any private proxy can do the job.
But Instagram, is extremely strict, and banns you right away if the proxy has been used more than 4 or 5 times, so not only private proxies are needed, they have to be virgin or nearly virgin
For example SSL Private Proxies have this "virgin private proxy" service, but sometimes they gave me 1 used (not intentionally), and they killed my account. Anyway, from my experience, they are the ones with less "error" ratio in the proxy assignment.
For facebook, I will stick to a simple private proxy same as twitter. The worst thing that can happen is they request a photo verification or a PV (mass planner has a great option to save the day in photo verifies)
In general, for social networks, private proxies, for other services (like seo blasts), you can use shared proxies, or random public proxies (depend if you are targeting your 1st/2nd tier)