Having used both, if you already know NextJS well then I wouldn't bother switching to Remix. If you want some of the Remixy API-niceness in NextJS land then you can use tRPC (for example, there are probably other options).
Nothing against Remix, I do like it, it just isn't differentiated enough from NextJS to both switching for me - yet, at least.
For work: NextJS, because Remix's future is now a little less clear. Also, there's 10x the help and documentation for NextJS. NextJS is where the mindshare is, for better or worse.
Nothing against Remix, I do like it, it just isn't differentiated enough from NextJS to both switching for me - yet, at least.