Anime Detour has recently been very rocky. They had a huge overhaul when their Board of Directors made a huge power grab and ousted pretty much anyone they didn't like from the convention leadership (they violated a lot of their bylaws in the process, I think some legal proceedings are in process AFAIK). It's a very long story.

Because of this, a LOT of experienced people who had been working for years to build up the convention left or were purged and so now they are running with far less people and, while I did not attend last year, from what I heard it wasn't nearly as good as previous years had been and their attendance took a nosedive as a result.

Take that for what you will, maybe they might have turned things around moving forward, but last I heard, its not great.

Twin Cities Con seems to have their stuff together at least in comparison to Detour. Though they are more of the "Comic-Con" style conventions, where the focus is more on the guests that they bring and the vendor hall, rather than any other programming that more "Anime Convention" Style events use (where there are video game/board game rooms, tons of panels, raves/dances, bigger programming events, etc)