SubmitHub is legit. Like it says in the post, it's very competitive. I have used them a few times. The response you get are mostly negative (at least they were for me!) but you do get responses and that in itself is valuable.

There is an interview with the founder on a podcast somewhere that's quite informative. I'll link to it if I can find it.

I had never heard of Soundcampaign though. Will have to check it out.