They are both significant operations, flap probably more so than implants.
It's important to talk to your surgeon about more than just the cosmetic appearance. How well do you usually heal? Do you tend towards heavy scarring, do old scars--if you have any--ache?Are you prone to infections? Stupid little things, how does you body respond to injury or intrusion. For example, if you have piercings, how have they healed. All these are indicators about how you may respond to different types of reconstructive surgery. My body hates my implants which, when I think about it, comes as no great surprise. I've always been irritable, and they irritate me no end. Others have no problems at all.
Having spoken to many women about this over the years I think it is reasonable to say that barring any incompetence, surgical complications and outcomes often mirror prior experience. Your surgeon may say 'This nonsense is why you should not join forums. Nobody knows what they are talking about.' but I think it is wise to have broader conversations than those about cup size and how long it will be before you should drive a car. Mxx