Both are nice revolvers in desirable barrel lengths, can't really go wrong either way.
27 will be heavier, softer shooting, and easier to eject since the ejector rod is full length.
19 will be lighter, will have more options for grips since you can do round butt or round to square butt conversion grips, but will be a little harder to eject.
27 would be harder to conceal if that is a consideration.