Normally, I would say that the CR-1 is superior. However, his K-1 interview is next week. You are much too far in the process to gain anything by changing to a spousal visa now, imo. He can be working in about 6 months after submitting his Adjustment of Status paperwork. He will likely have a Green card about a year later. If you marry now, it will be 18 to 24 months before they can immigrate. The average time from submitting an I-130 to spousal visa interview is 740 days as reported by other Visa Journey Members.
Get a well-qualified joint sponsor for both the I-134 and the I-864. I would proceed with a K-1.
Had you asked these questions a year ago, my answer would have been totally different.
On a side note: Nursing is a great career with plenty of job opportunities and good pay. When do you finish school?