Rivals / 247 both miss on their fair share of prospects and they also have a fair amount of head scratchers. All things considered, Rivals still has a good core of evaluators and some really good regional writers (Hubbs and P. Fort for example) that at least allows them to keep certain fan user bases over 247. 247 has the edge in terms of technology, user base, contract (CBS bought them out) and staff. ESPN is probably 3rd in terms of football evaluation, but I rarely trust them - they don't bring much to the table nor do they have any names that carry weight in the recruiting industry. Scout is completely hit or miss and really the only reason they've stayed afloat this long is because of a few regional basketball writers. Their football rankings aren't bad, but they aren't to be taken that seriously.
In terms of evaluation I consider 247 / Rivals almost equals, there isn't one that's clearly ahead of the other. 247 often evaluates prospects quicker than Rivals and they tend to update their rankings more as well, but in the end once the rankings are completed and you compare them to their counterpart, there isn't a ton of difference. They are all seeing the same camps, film, prospects, talking to the same coaches, trading the same info, etc. You get a clear sense of who is going to be a 4 star and a 5 star, especially once you see them up close. Only 247 gets a couple exclusives say at The Opening and at the All-American bowl, but even then evaluators and writers from other sites are there as well, soaking up the same information as everyone else.
1 247
2 Rivals
2 ESPN
3 Scout
The 247 Composite isn't a service. Its an algorithm created by 247. but we all know this...
I know everyone wants to believe 247 is leaps and bounds ahead of the competition in terms of evaluation, but in reality I don't think this is the case. They are maybe a little better than Rivals (in terms of football evaluation) but not by much.