Don`t wanna sound like a jerk, but could this have been discussed in the FFXV thread that we already have here? Also what Tabata probably meant by that statement is that the villain might not be strongest one of all FF bad guys, but that he would be the new most memorable one. Someone that would surpass villains like Kuja and Kefka, which most of the FF-fanbase praise to heavens and beyond.
But on the topic itself. Well, there are several characters that people have speculated to be the villain of FFXV. The ruler of Nifelheim, Emperor Aldercapt, the mysterious Hooded man seen in past trailers, and the umbrella and fabulous hat guy seen in the 2013 trailer.
Personally I see Idola as someone similar to President Shinra and Rufus from VII, Gestahl from VI and Brahme from IX. They seem t be a major threat and they are, but the real villain is pulling the strings in the back round, controlling them and their motives(nut we never know, they could surprise us). I could see either the hooded man or the umbrella guy be this shadow puppet master. The hooded man with his wordplay gives me some Kuja vibes, and I could see him being a theatrical villain. I read an really interesting theory about him once, and I think I posted a link to it here a few weeks back. Also I have seen a theory were it was speculated that the hooded man was actually Prompto, because the hooded man and Mr. Argentum share a few facial similarities: the hair, the face structure is similar etc...
The umbrella guy could be another puppet master, maybe not the main villain, but some one who manipulates others and is there to enjoy the show, and maybe to advance his own goals. Similar character to Reno from VII and Axel, especially similar to his personality in Chain of Memories. Also when I look at that umbrella, I would like to see him have similar fighting style like Neo from RWBY:
Smug and fabulous.
What I personally want to see form this villain? That he/she is complex, that the villain is smart, has cool looking and amazing powers, good personality. So the basic stuff.
EDIT:
Ninja`d by Vanitas666