I've tried a few subscription services and I love Keel's the best. The biggest difference is that they show the Pros' returns and investment fields before you pay. At least, that gave me a good idea that I am not just paying someone who claimed how good they are, but they actually have proven track records.
I was skeptical how this can be done till I learned that they integrate directly with the Pros' brokerage accounts to verify those data. I love this idea and the possibility that I can shadow Pros' trades!
With Keel.io, I paid $10 a month to follow a professional investor and to ask him questions about his recent trades. Using this information, I was able to significantly increase my investment returns!