Since I have finished all the Male love interest endings I can say without a doubt that Morgan pretty much blows the rest of the male love interests in the water.
So my ranking would be: Morgan>>>>>>>Jonathan>John>Sebastian
Morgan's interactions with Heileen seemed more serious, had more depth to me and it helped that he had the best personality within the potential love interests. Jonathan is only better than John because I found he's ending and the CG sweet and that he at least seems to be much more classier than his brother, even if it makes him stuck up at times. I like john and he is sweet at times but i'm not particularly fond with perverted womanizers which can also explain the reason why Sebastian was my least favourite out of the 4.