掲示板 Forums - Different words for bright/cheerful?

What’s the difference between あかるい and めいろうand ほがらか ?

Think of 朗らか as a "softer" version of 明るい. To quote a native: 朗らかな人は明るいに加えて、優しい、穏やかなニュアンスが入っている気がします。

So in addition to being 明るい, they are also 優しい and 穏やか.

There's also the usage note on 朗らか: "Serene, tranquil version of cheerfulness." (by Keitsubori {稜堀華尉})

I'm not sure what あいろう is doing here. Did you meant 愛想 or 愛嬌, something else?

Yeah, it looks like 明朗 has basically the same meaning as 明るい when describing someone. It just feels more formal or literary. I don't think I've ever heard it in spoken Japanese. Not saying it isn't used, just that I don't remember coming across it.