This was very hard!
Based on books I go back to as “comfort reads,” I chose the following (in no particular order):
Castles by Julie Garwood
His At Night by Sherry Thomas
Again, the Magic by Lisa Kleypas
Voyager by Diana Gabaldon
Romancing Mr. Bridgerton by Julia Quinn
Runners up include: The Bride (Julie Garwood); Devil In Winter (Lisa Kleypas); What I Did For A Duke (Julie Anne Long); Secrets of A Summer Night (Lisa Kleypas); Kiss An Angel (Susan Elizabeth Phillips); The Devil You Know (Liz Carlyle); Bet Me (Jennifer Cruisie); Tempt Me At Twilight (Lisa Kleypas)