All though they were both kinda flawed, I prefer the Ben version. It felt like a round about conclusion to both Kenny's perceived failure to save Shawn and his feelings towards Ben. I think it would have been more effective if it wasn't so transparently obvious there was no way Kenny was going to fight off all those walkers.
Instead, maybe initially there's only a few of them and you watch Kenny successfully fend them back for like a minute or so before two dozen more flood in from stage right and only then it becomes clear there was no way out. Basically make it look like a long shot before making it apparent it was a suicide mission.
The Christa version actually bugs me because it seemed pretty uncharacteristic of her to act so rashly. Excluding when Omid is in danger, she was typically the most cautious member of the group. Watching her so casually risk her life for something we really didn't need just felt out of place to me.