I have not created new accounts on Twitter with any proxies for a quite long time so I can not give you any recommendations but you might check out this link blackhatworld.com/forums/proxies-for-sale.112/ and make sure to research the reviews on the forum and on the Google before purchasing any service.

I advise against using shared proxies for creating an account on the social media sites, since most of them are already blacklisted or used by someone else.

It is better to safe to use dedicated proxies and ideally get a one account per one proxy so you do not get flagged and trigger many verifications that become more complicated.

I do use Twitter, but I very rarely create a new account now since I have create dozens of them already and I manage them. I use this site for promoting my adult websites and even though links from social media are no follow, they can help with improving your rankings so there are many benefits of using Twitter and it is just traffic based.