I used to alternate. I would typically use my real name on comments or posts (even in IRC) when I wanted people to know that what I was saying was something that I was willing to put my IRL credibility and reputation on (i.e., I wasn't hiding behind a keyboard).

I also like the freedom to post my thoughts free of that reputational damage and see how people react, and ideally to understand why my thoughts and perspective might be wrong (and I know there's a certain implication there in modern times, and no, I've never done or said anything outright hurtful to people).

Then one time in 2016 I got "dox'd" for making a comment on Bruce Scheiner's facebook page during the 2016 election. The post merely stated that Bruce was allowed to comment on political topics (a previous commentor had said he should just stick to security topics).

I was then harassed at my workplace, with said commenter (presumably) claiming I was being racist and homophobic (I'm gay) via email.

Since then I've never used my real name.