I use mayo because my wife and two of my kids are lactose intolerant, but as long as you use a decent mayo (e.g. Dukes) it comes out pretty good. I have also found using a slight bit of seasoning (mix of salt, pepper, garlic powder, onion powder, maybe cayenne) kicks it up a notch. Sure, using salted Kerrygold butter is slightly tastier than mayo, but it isn’t enough to make a big difference IMO…