Both will flow the same as it's internal diameter doesn't change ,5 bolt will be a rigid clamp where a V band can flex a little.... Issue with V band when welded can distort the sealing surface even with tig if incorrectly done...5 bolt is best replaced with studs and nuts as sometimes bolts can seize and snap,a steel bolt that has many heat cycles builds up it's hardness and will be difficult to drill out.
If you find a v band turbo that you can't pass on but want the bolt style you can weld a flange onto the housing to convert it.....