I really don't have much of an imagination for long-term "monikers" so have always just ended up using my first name/nickname with either my last initial or some other random-ish suffix, or when I really want to stay (at least superficially) anonymous, some sort of anagram-ish variation of it. And since "Michael" was the most popular name for males in this country from shortly before I was born until the turn of the 21st century, give or take, none of my online IDs or my email addresses has ever really stood out enough to attract anything but randomly generated spam.
[ETA: Upon reflection, that's not quite true. My first non-numeric CompuServe address was my full first and last names. At that time, inter-BBS email among "civilians" was still pretty rare (and CS itself was pretty heavily "moderated") and the Web was still at the idle musing stage, if that, so I wasn't really worried about privacy. But I let that account lapse even before the Web went public and commercial/blackhat spammers had really even come into existence in a any noticeable way...)
If I'd ever used my first plus last name, on the other hand, I'd have been far more visible online than I've ever wanted to be (especially before the late 1990s when large numbers of Russians started immigrating here for the first time in many decades) and if - God forbid - I ever used both plus my middle name, I could be pinpointed from high Earth orbit through heavy cloud cover by a near-sighted, astigmatic astronaut. Which is precisely why I've never been foolish/dumb enough to do that.
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