If being together faster is your main reason, then you can go with the K1. But be very aware of the limitations such as your fiance will not be able to work, travel back home, or sometimes can't even get a driver's license for several months after they get here on a K1. This is a huge burden for a lot of people. Many immigrants feel trapped being stuck in the house for so long.
No only that, the immigrant has to file Adjustment of Status (AOS) after marriage which is more money and more documents to file. And the price for AOS is going to be over $2000 after Oct.
And finally, the pandemic has shown that K1 visas are not processed at the same importance as spousal visas. So during a shut down, the K1 visa interviews may get put on hold while spousal visas continue to be processed.
So basically, you have to weigh the pros and cons. Getting here faster only to be stuck here with no job and no ability to travel may be a deal breaker for a lot of people. With a spousal visa, an immigrant can work immediately. and there is no AOS so there is not extra costs or paperwork.
