I really like it. Much better to go for a name you love, rather than worry about how popular it may or may not be, as that's not something you can control. Statistically, Ruby is nowhere near as popular as it was in the 00s, but obviously there's still a chance of it being repeated at school etc. That can happen to any name though.
I work in a primary school and have seen the lists for next year's Reception (not a single Ruby. In fact, we only have a few in the whole school). Out of 80 odd kids next year, there are only 3 repeated names. One is an Arabic name way out of the national top 100 (same pronunciation, different spelling), one is a name which was popular in the 90s/00s but is way down in the top 100 now (although one is double-barrelled with Rose so she may or may not go by the full version, making the two sound slightly different), and one is an old fashioned name which is on the rise but still only in the lower realms of the top 100. It has several nickname options, so there's every possibility the two children may go by slightly different names if their parents do shorten it. We will only have about 8 kids with top 20 names, all of whom will be the only one in the year group. No Olivia, Lily, Ava, Amelia, Isabella, Theo, Freddie, Jack etc, that posters on here will tell people they must avoid as they'll be one of 3 in the class etc. My point is you can never predict these things. The parents of the children with repeated names perhaps won't be expecting it, whereas the ones who chose a top 20 name probably are and will be pleasantly surprised. This picture is repeated in most of our year groups throughout the school. There's only ever a handful of repeated names in each year group these days, and it's definitely not always the names you would expect.
It's much better to just go for what you love, and what will be will be in terms of however many others they meet in the future. People choose from a much wider pool of names these days. Repetition at school is rarer, but when it does happen it can be rather random anyway.