Slayer ... very different from Carcass, Carcass is one of the founding bands of Grindcore. Slayer is one of the greatest Thrash bands of all time.
At the Gates ... one of the founding bands of Melodic Death Metal (AKA "the Gotenburg sound"). They are not similar to Carcass.
In Flames... they borrowed a Lot from At the Gates and Amorphis, added their own twist to it, played their own style, took Melodic Death Metal to the next level (up to Colony at least), Again, not really similar to Carcass
Death ... pretty much undisputed godfathers of Death Metal. RIP Chuck! All around an awesome band, however, they really aren't very similar to Carcass
SWScorch, the bands you mentioned really rock, however, you are all across the board, black metal, melodic death, thrash etc ... but nothing really similar to Carcass.
Carcass is unique, you will not find anything like them, there are other bands that try to mimic the style of Carcass (see my above post), however, take all recomendations with a grain of salt (especially mine) since everyone has diferent opinions.
I have been naming bands that I think play the same style, others look like they have been naming bands that play with the same level of skill.
In any case, listen to whatever sounds good to you.
PS ... for anyone's who's suggestions I have suggested against for "not sounding like Carcass", that doesn't mean I don't like those bands or that I'm attempting to thread crap. It's just because I don't think they really sound like Carcass
