Out of the main and secondary characters, I like everyone. Well, except for Shigeru and Shinji, I hate them.
I like Satoshi because he's always such a derp. Kasumi is entertaining too, espcially when she yells at Satoshi. Takeshi's obsession with women is always funny. As for Haruka and Hikari, while they aren't as funny as Kasumi, they are very nice, and I really like their singing (well, okay, I like everyone's singing, but that's besides the point). Iris is pretty unique due to her being adventerous. As for Dent, he's cool, but he says 'taste' a little too much, I love his design though.
Um, who haven't I covered.... well, there's Masato. I haven't seen enough Advance Generation to really form a good opinion on him. I was able to get a better opinion on his sister, Haruka because she talks more. Then there's Kenji, who's cool, since well, he draws and I do too. Then Musashi, Kojiro and Nyasu are entertaining to watch, and I like the backstories they gave them.
Oh, crap, forgot about Kosaburo and Yamato. Well, Yamato is just a jerk, I don't like her. As for Kosaburo, he's cool I guess.
All in all, I can't decide, all I know is I hate Shigeru and Shinji, so definatly not them.