In thinking about Doug & Emily's conversation regarding flaws, I think Emily asked the wrong question, but Doug responded to her intent. Clearly Emily, like any reasonable woman, wanted to know if Doug or any of these guys are as wonderful as she hopes they are, why are they available.
So Doug's response of "I'm too good a dad" was really saying his son comes first before a romantic relationship. In my opinion that's something Emily having Ricki shoud appreciate. Plus his ex's complaint about his not washibg her car enough clearly meant he didn't do something she viewed as showing he cared about her.
So in my opinion, the right guy for Emily, or any woman, is someone who understands what matters to her. To me this means I hope she picks Sean since I think he's one of the few guys in the world who gets it. He told Emily, he may never have been married but he plans on following his parent's example of continuing to date, as in continuing to do what made them fall in love in the first place. IMO, that's the perfect recipe for a happy marriage.