Sex Pistols

Both are yaoi romances featuring cute schoolboys. I think you'll also see a lot of similarities between the art styles of the two, since both feature crips lines and make heavy use of pastels. 

Both yaoi with brilliant animation. Focuses on two sets of lovers, similar to Junjou's three. Similar soundtrack and sense of comedy (intimate moment right before adorable awkwardness or something/someone interrupts).  

Both anime are BL and both have a character that doesn't accept the fact that he is in love with a boy. 

These are both yaoi's,both have nice art and hilarious story/moments.