If you are really seeking for the ranking then the link given would already shows on what OP is seeking. Seems like he didnt tend to response peoples answer here.This is somehow confusing on what thing he does mean. Popular altcoins? There are lots if you do really see on marketcap or maybe hes pertaining on famous ones as of now .
well, it is actually very easy to know which altcoin is trending now and people have trust with it
My suggestion would be : just go to big exchange site, take for a example, Poloniex.com
go the trading section and the just sort the coins on volume, you'll see then which coins are popular now
if you do such monitoring on regular basis, soon you'll learn enough about altcoins
and to make thing easy - I will name a few, just to reference - ETH, ZEC, LTC