If the answer is familiarity, another way to phrase that answer that might get the point across better is,
I don't know enough about tool Y to even say why I might not want to use it. But I know tool X. It does the job I need it to, and I don't want to take the time to learn tool Y. Learning tool X already took too much of my time.
At this point, you're clearly not showing off. Anyone who thinks you're showing off when you're saying you don't want to take the time to learn something is probably going to think you're showing off no matter what.
This is basically the reason I give people for preferring vim to nano. I've met a few people who can't understand how I can possibly know vim the way I do, and not have time to learn nano. But knowing how to use nano isn't universal knowledge, and I got my introduction to unix nine years before nano even existed. While it's true pico existed already, that was part of pine, and my introductory mail tool was mailx. I didn't learn pine until after college, at which point it was natural for me to spend more time learning how to get it to use nvi for my editor than to learn how to use its default.
All I really know about nano and pico are that they're basically always in insert mode, and there's control keys to get them to do special things. Hit enough control keys, and I can get out of them. But I've no idea how to do macros, or shift blocks, or run scripts on portions of the text, or anything.
(Disclaimer: I've since been told that nano and pico don't have macros, can't shift blocks, and can't run scripts on portions of the text. I still wouldn't claim to know this, because it's just something I've been told. For all I know, it's just FUD. Even if it was true at one point in time, that was years ago; I've no reason to believe it's still true. But what is still true is I don't know how to do those things in those editors... or save a file or load a new file or so on. I know how to in the editor I use, that's enough for me.)