Ehhh, I'm not sure this constitutes an unpopular opinion. If you go by sales, "plain" chips are number one. The next closest flavor is bbq, but the sales are half what plain are.

Now, it certainly isn't the guaranteed most accurate metric to use. Plain chips being plain, they're the go-to for dipping and when you want something that everyone that's going to have chips at all can at least tolerate. So the sales vs actual preferences are probably skewed. But are they skewed to the degree that double the sales would end up being reduced enough to even tie with bbq?

I doubt that.

What I wouldn't be surprised to find out is that specific brands of plain vs bbq vs cheese or whatever might shift things. An example might be that Lays bbq ends up being the most popular chip overall by brand and flavor, but plain lays would be a close second. And lays is the top selling potato chip brand, or was the last time I looked (you'd be surprised how often people wonder about the general subject at parties while nibbling on chips, so it's nice to be able to make conversation).

I tend to agree with you overall, btw. With only minor exceptions, if I want potato chips, I want to taste potato. There are times when a specific flavor goes better with something (bbq with burgers, imo is better than other flavors), but plain, salted potato chips can go with damn near anything. And they're good by themselves, depending on brand (I am not a lays fan by themselves).

Mind you, salt & vinegar is essentially the same as "plain", imo. Yeah, the vinegar makes them not what you called plain, but truly plain chips without salt are pretty damn great, as are plain with salt & pepper. So there's a little wiggle room in what exactly can be a plain chip or not. I say it can't be a blended flavor, but can be simple additions you might make at a fry/chip stand. Salt, pepper, vinegar (usually malt). Any combination of those doesn't require any extra effort to make happen, whereas any other flavors I can think of would mean having to prepare multiple other ingredients, or would constitute a dip/condiment.