Well you "could" get every wallet on that list and do a rpc/json poll of the getmininginfo command and get the diff etc.. and then find out what the blockreward is and value of coins and then do some math etc.. etc...  for example if you have a favorite exchange, instead of going around figuring out who is paying the most for a set coin you do the math for just your favorite exchange and then mine what is most profitable for that one. (lots of math to do on a sometimes minute to minute basis so best to find a way to automate that. 'cause daaaaaaamn)

*OR* you could go to places like whattomine and coinwarz and just accept they don't have many of the coins in their lists.

I'd go with whattomine and coinwarz, not 'cause I can't do the math involved, but because I'm a little lazy that way.