First up, the names (from 2017's Top 1500) that have changed most strongly from masculine to feminine:
This isn't in order of popularity, but in order of biggest gender-swap. Emerson, for instance, went from a ratio of 114 boys for every girl to about 3 girls to every 2 boys; Reese from 18 boys per girl to 5 girls per boy; Briar from 3 boys per girl to 2 girls per boy.
[all of my calculations are based on changes in percentages, which weights the results toward more popular names. So above, Hensley goes from 6 boys/girl to 26 girls/boy, which seems to be a much larger shift than Leighton, which goes from 7 boys/girl to 3 girls/boy. However, Leighton, given to 115 boys in 1992, was much more popular than Hensley, which was only given to 8]
Next, the names that have made the largest shifts from boy --> unisex (but are still more common on boys):
Reece had the largest change of any name, going from 206 boys per girl to only 3 boys per girl. Ryan, easily the most common of these names in 1992, dropped from 68 boys per girl to 9 boys per girl.
While there are a lot fewer of them (and they were all a lot less common to start with), there are quite a few names that went from feminine --> masculine. Here are the ones that shifted most:
The biggest girl-to-boy shift, Yael, given to 61 girls in 1992 and not on the boys' list at all, was given to 197 boys and 116 girls last year. Elisha (presumably seen more as an Alicia knockoff in 1992, not a Biblical prophet) went neatly from 2 girls per boy to 2 boys per girl. Joan I again assume has gained usage more as a Catalan boys' name than as an "outdated" English girls' name.
There were also a few girls' names that have made strides toward being unisex (well, again, in most cases):
Alexis, the most common of these in 1992, has dropped from about 11 girls per boy to about 3 girls per boy (mostly, I assume, to it falling out of fashion as an English girls' name, but remaining popular as a Spanish boys' name).
Interestingly, Jamie and Robin, both names "stolen" in previous generations, were both about 4x most common for girls in 1992, but are now both more popular by a ratio of only 3 girls for every 2 boys.
There is hope for reclamation yet. ;)
If you want to see the whole list of gender-shifts, it is here, on Google Sheets.