Lincoln stable value fund vs S&P Marc 5% Fixed Index Annuity ?

I currently have about 50% of retirement funds in a 403 B employer invested plan, called the Lincoln stable value fund. {Classified as an annuity} It pays about 2.8% per year with no risk to principal. Been doing same for several years now. I was thinking about switching to the  S&P Marc 5% Index. It is a Fixed Index Annuity. It had been yielding 4 to 5% annually {average yield} for the most part.  Any suggestions or advise from community members?