Its hard to answer that because without being a customer of those services I can't comment. Anyone could claim that they're better than XYZ service but lets be honest until you're a customer its unprovable.
IMO, Content removal is a pretty simple beast ....know your clients content, learn/know the places it gets shared and relentlessly police those places for removals. I think knowing a clients content is actually the hardest part and it gets progressively more difficult as your portfolio of clients expands and their content diversity increases.
It wouldn't be easy to learn every market (teen, asian, gay, tranny milf, etc etc) and all of the individual sites/prodcers content (by sight).....especially in an age where watermarks get removed and uploaders mask the contents description. In addition there are very specific places where different content is shared and a broad portfolio of clients (for me at least) would mean having to join and search hundreds of forums.
Therefore, I limit myself to micro niche and know the market inside and out. That way I can join all the relevant forums etc and police them accurately, which in turn means I don't miss anything for my clients and its time effective.
As for finding the material, I personally prefer the down and dirty approach....that basically means I'm in all their forums/blogs/imagedumps/message boards etc etc and checking the posts manually for removals, in addition to worming my way into their group. I'll follow any relevant nugget of information in the hopes a name is found and sooner or later I'll have a dosseir going and find my target ;)
Thats just the way I personally do it.....I do like my sleuthing
