First character, Faelin, is and was Forest Elven, originally dubbed Wood Elven, since there was no written culture lore at the time. Reason being very simply that it made sense with her heritage. After lots of changes and backstory reforms, I found that it still made the most sense to suit her starting circumstances. Italicised because it does not necessarily reflect her belief system, upbringing, or subsequent lifestyle: on account of how RP shaped the character, it remained a largely biological/instinctive part of the character, and less a cultural one.
Second character, Evelyn Arwedhel, is and was Silver Elven, and quite fortunately her former lifestyle fit beautifully with the newly written culture lore. The choice to play this culture, though, was originally very much by design. Something something related to both Moor Elves (formerly Dark Elves) via marriage and fancy Silver Elven nobles by birth, shifty arranged marriages to bolster various reputations and claims. Stuff.
Third character created (though the fourth I played), a certain Jarl, had to be human to have and keep her position in House Lonmar, and to align with the traditions of the new culture I had been writing: the Norvägen. As I had said I would play Draco's successor in order to manage the House, human it was - as being born otherwise would have led to a life beyond the borders of the Northern Kingdoms, and the character would not have been able to take that role.
Fourth character created (though the third I played), Rissy, was a human because they are the most populous and non-specific of the races, and that suited the typical peasant background - her having been raised on a farm in lands around a town some miles away. Non-specific, one of many, but very much an individual, and overall very robust, if blunt in her ways. It felt fitting for humanity.
Fifth character created (though never played), "Old Mab", is human because I wanted to try playing an aged character - something already out of my experience, and therefore comfort zone. I did not want to have to get my head around the very different ethics, traditions, and values of an entirely different race at the same time - also things clearly outside any first person experience of my own.
Sixth character created, Safri'kah, was created expressly for the purpose of experimenting with a character of a very different physiology and culture to the rest, a Nakat, and while I'm unsure whether I ever quite did that justice, I enjoyed the experience and think I've learned a bit from it.
Overall, though, and over time, I do feel that I've personally been drifting towards playing only human characters in the future. There's just such diversity within that race alone that I find it utterly inexhaustible, and often easier to relate to in simple ways, which opens up the opportunity to make a character more unique in the subtle ones.