<p>MathCamp is by far the best, (and hardest to get accepted to), there is a good forum comparing them all, which I will post when I find it, </p>
<p>yes it’s worth it to apply to all of them</p>
<p>Ross/Promys are very similar except for pricing, length and location, however Ross is easiest to get accepted to, and I recommend making sure to prove your questions in multiple ways, since they were made easy for a reason, to more analyze your though analysis. HCCISM is more of a quirky math program, for really cool obsessed math nerds, 
Ross is outright number theory to the max, </p>
<p>there are other’s as well, such as AweSomeMath, which is olympiad prep, and Utah Math Honors summer math program, that one ain’t as prestigious but it really decent, free and runs during a time when none of the others run, except the 6 week programs, or 8 week ross program.</p>