L.L.
I think the scarring may have more to do with the patient's scarring process than anything else. I've had all three -- sutures, staples and glue -- and for me, all healed equally as well with very little scarring at all. All the scars look the same, no differences for me. I'm not prone to keloidal scars, so I think for me any option is fine. Maybe if you're keloids, one would be better than the other but talk to your Dr.
I did have sutures that broke when my Dr was taking them out. I ended up having them for years afterwards and were only removed after during my c-s. They would itch from time to time, but that was the only side effect from the sutures.
I'd discuss with your surgeon and see what he or she prefers. He or she may prefer one method over the other and I'm sure would be happy to discuss with you.