I immediately think Seager and Cano. If there's agreement on those there are undoubtedly a couple more at least (though it might take VsL or VsR split to highlight some)
But I'm not sure the phrase "Gap-to-gap" intuitively describes what it is intended to. It initially sounded to me, years ago, that it meant players who generally hit from LFC gap to RCF gap. Looking at the list of players described as such, it seems it's meant to include as far out as the 1b line "gap" and 3b line "gap". Edgar Martinez was called this at times. Looking at the players who have been described as gap-to-gap hitters has given me the understanding that it's meant to say they'll collect many doubles and if they have speed some triples. Gap finders seems more intuitively apt a description than gap-to-gap. They tend to hit the pitch they're given and do what they can with it, using the entire field. That's if I'm understanding it correctly. I have had trouble finding spray charts of anyone ever to hit noticeably more from LCF to RCF than outside it anyway.
But then Edgar would fit in all 3 categories to an extent. Power would probably be the one to drop from a discussion first so how do you choose whether he was gap to gap or contact?