The best one is Minasan no Okagesamadesu! For those variety show links and crazy, sick shit goings on, it's just strange like no other Neo game. It's sort of like whacked out a board game except you play Mahjong on the spaces you land on. If you have seen (& liked) the Ping Pong Club anime series, you will take a liking to this game. All the same roots, or so I'm told.
And the worst? Ummm.. I don't know. I never played much of Baka Tonosama so I can't say for sure. Of the three I have played (Minasan, MJ Kyo Retsuden & Quest of Jongmaster) I liked MJKR the least, though it's not to say the game was crap or anything. You go around as some, well, on the box he looks like a Japanese porno star, I guess he's a playboy, but you go around gambling and what not, playing the game, and I remember I eventually got some girl on the hotel room bed, got her down to her bra & knickers, and something happened (I think our opportunistic hero shagged her), then her piping mad husband/boyfriend challenged me to a game of Mahjong the next day, and I eventually hit Esc so what's beyond that I don't know.
Good luck deciding.