«Lunabrite» has light purple leg padding on navy blue canvas, giving it a cool relaxed feel while appearing bold and unique. (babyslingsandcarriers.com)
With the Kobo's preloaded fonts, you have the option to customize the weight so that you can make the text appear bolder. (blog.the-ebook-reader.com)
I found that adjusting the contrast settings can make the Sony's font appear bolder, but also makes the text appear rough around the edges, depending on how dark you set it. (the-ebook-reader.com)