I use MorningFame, it's great for making sure that your video will have good SEO and it's nice to see the analytics through it, it tells you how videos are doing in comparison to each other and say whether the first 48 hours of a video were good or not and stuff like that. TubeBuddy is great for doing bulk actions on your videos, for searching different search terms to see how easily you'd be able to get your video under that term, and for little things here and there like replying to comments from notification. Both of these have free and paid versions, MorningFame is a lot cheaper than TubeBuddy but it's worth trying the free version of both.