Could you recommend some private proxies to me?

Hi guys,
I need some private proxies which:
1.are private
2.the thread is large
3.can be tested
4.can be replaced if there are some problems with it
5.have high qualities
And by the way I need a large amount of them. The quality matters a lot.
Do you have any recommendation?
Thank you!!

I use InstanProxies.com for my social media campaigns. They are good, especially for the cheap price and they have gladly replaced proxies for me and are co-operative in general.