I understand why you would choose 3 sharps. I've talked about this (the V chord thing in general) with quite a few musicians and nobody seems to agree on how "it should be written". I write it like I would write it for a blues. A blues in E is 4 sharps, even if all the chords are V chords. But, even then I get comments that it should be 3 sharps by some, while others agree on 4 😀