Depends what company (for both gigs) & what previous experience you have.
I have an ex-colleague who gave up a 737 right seat to take RIGHT seat on an ATR with JetTime flying the SAS contract (lifestyle decision I believe)
At the moment a seat with Wideroe on a Dash is probably more highly valued by Norwegian guys than a seat on a 737 with NAS , but . . . usually. . jet is best. If you have no jet-time & the rating is paid, go for the jet, if the price is "reasonable", I would also say go for the 737.
Is there any chance at all of the contract being extended/ renewed at a later date ? 500hr is not too unique, a lot of guys with this level of experience waiting their 2nd jet job after a (usually) P2F contract.
Very few good turboprop jobs/operators. . not so many good 737 jobs either, but at least a few more bucks (normally) & a better chance to change to another jet type.
If you search there was a similar thread here within the last year & it was done to death.
Fair to say, you pay your money (or hopefully THEY pay you) & take your chance.
No right or wrong decision . . you will only get personal opinion disguised as advice here
