As I am a social media marketing manager, I have used many tools till now.
Out of them I was really impressed with the tool FollowerAudit, and liked its functioning.
FollowerAudit is a Twitter analytics tool. This tool provides amazing different features which you won't get in any other tool in the same pricing plans.
It is an affordable tool. You will get the following features
FAKE FOLLOWERS - Identify the percentage of fake followers in your or any other public account and also get a list of all fake followers,
INACTIVE FOLLOWERS - Identify the percentage of inactive/ghost followers in your or any other public account and also get a list of all inactive/ghost followers,
TRACK FOLLOWERS GROWTH - Track your followers growth daily, weekly and monthly.
TRACK UNFOLLOWERS - Get real-time alerts whenever some will unfollow you and a list of all the unfollowers,
GET DETAILED FOLLOWERS ANALYTICS - Get other detailed followers analytics like - identify most-followed follower, list of verified accounts, last active date of followers,etc.
COMPARE ACCOUNTS - Compare multiple public Twitter accounts stats together.
TRACK YOUR COMPETITORS - Get all the insights mentioned above for your competitors too.