Curved. We put a curved rod on a standard 5' tub and eliminated all the overspray. The ends go in the tub further than a straight rod but the middle is further out. You have more room where you stand and less where you don't stand.

I think hendricus missed the fact that you are installing a shower only. If you are replacing your tub/shower with a shower that only has a curb, you shouldn't use a curved rod. If you do, the outer edge of the shower curtain will hang straight down outside the shower curb and water will go on the floor. If you move the curved shower rod inward to prevent this from happening, the ends of the curtain will be further into the shower than with a straight rod and you won't gain any space.

Thanks kas - yes that is my concern exactly. Although I think I would prefer the look of the curved rod, I think with SHOWER ONLY (NO TUB) that I will be watering the floor alot if I go with the curved.

I agree with kas.