Have you tried @ginabot @crypto-econom1st ??? It's a really good bot that I use to have a seperate follower list specifically for following certain people - like a subfollowing list. Super helpful! There's also a relaunch of an old tool very helpful in identifying people you may follow that have become inactive. That one is here: https://steem.agency/follower/following
It's a bit easier to unfollow know the account has not been active in awhile.
As of yesterday I use Ginabot. So far only to see who upvotes me and for which value, in case someone mentions me and who starts following me. I am thinking about sending all my new followers a welcome message to ask them why they start following me.