Gameplay is absolutely more important, but if the graphics are so ugly that it hurts your eyes then it is hard to play. In 4, I like my characters. I like how they look and develop attachments and stories for them. The personalities ingame are not impactful enough to be brought to life without a lot of imagination, so I had to like them for them to exist.
Not so much in 3. It took me a long time to design a character that I did not despise the look of to be my absolute favorite. It was also much easier to craft a variety of characters of varying importance and personality. Note here, I really disliked 3's graphics. I prefer 4's, but I would have been more than happy with the main game of 3 with 2's graphics.
Anyway, even though I despise 3's graphics and prefer 4's, I still consider 3 (and honestly 2 when solely based on live mode) the superior games because of the available gameplay.