If you get Corian (or any of the other similar type of products – Hanex etc) it will scratch – that’s a gimme. That’s why until recently none of the darker colours were approved for kitchen use as they showed all the white marks.
Recently, however, Corian have released what they call ‘Deep Colour Technology’ which basically means that while it will still scratch, it scratches darker so you can’t see them. With a bit of care, however, it will clean up like new and can last years.
If installed properly (and there are some not so good fitters out there) the joints will be difficult to spot giving a really good finish.
If the worktop does get damaged in any way, it can be repaired with whole sections being able to removed and replaced with new sections if necessary.
IMO, it’s no better/worse than granite/silestone, just different.
If you do go down the Corian route, take your time researching the fabricator as this can make the difference between a good job that’ll last years and a shabby one which you’ll never be happy with.
I work with Corian on a daily basis and have Granite worktops btw.