Sonic's Friends Aren't Innately Shitty, It's Just How They're Used
And I can't wait for someone to come up and disagree with me about this.
For one thing, I see nothing wrong with their personalities or designs, except for some of the post-2008 characters like the Deadly Six. They look fine. Well, they certainly do compared to the inanimate objects with googly eyes in Banjo-Kazooie, or the terrible characters of the Rayman games. Their design style generally still follows the mood and contours of the characters established in the Genesis era, so there's no real clash unless counting monsters of the week. They are all instantly appealing.
And about them all going fast... not really. Knuckles has been argued as a bit much, but I have heard it is his dreads that can push him faster. In later games, they also slowed down him and Tails, and he has a lower jump. Amy? Amy doesn't even curl, but jumps higher and has a different playstyle, as shown by Advance 1. The other characters all do seem to move slower than Sonic, and those who can move to his speeds have justifications (Shadow's Air Shoes, Blaze's fire powers, etc.) While their alternative gameplay is jarring, it's still better than that snowball level (WHICH WAS SONIC) and the Werehog (Who could have been better, but still was Sonic), let alone some other things that I'm not gonna bring up because they'd offend certain people.
When they don't, so far they've each came off as fairly distinctive (Advance, Rush, Chaotix, SBK), or rather clonish (Heroes, Rivals), and I prefer the more distinctive gameplay feel, as shown by the fan-game "Sonic World". They should each have different abilities and things to do even if they don't go as fast, and should be able to be ignored (except maybe for achivements so we can get people to like them).
And as for story, sure, they've recently been useless, but this also includes Knuckles, who is COMPLETELY useless in Lost World and had no reason to be there. Even the non-useless ones like Sonic himself are completely unlikable jerks. For better uses of them plotwise, just look at any of the comic series of the franchise, or most of the TV shows. A few games, like Black Knight, also had pretty good stories. "No need for good stories?" Just get them involved in the simple plots you want. "I don't want them shoved in my face!" Don't include them in the story at all, and just make them extra characters ala Crossy Road, which is what they should be doing now.
Voices? They have options for English, Japanese, or in later games also Spanish. They should also have an option for "none".