The F3 menu would be nice, it's extremely useful in the Java edition when making maps. At least give us debug controls!
I'd also like to see the Minecraft Pi API added. It can be limited but at least it'll bring more sales to Microsoft/Mojang coming from schools (Doesn't matter because they're the same now).
Shaders. We all want the game to look good. If you visit Shadertoy, you'll be surprised how powerful shaders are! Seriously, you can use shaders to make your inventory round! They're not limited to shades, they were just originally used for them.
What I would like to see removed, though, is the Marketplace. It's the most unused feature and is aimed at little kids. Most mature Bedrock players never use it and it is a cash grab.
Bedrock lacks a ton of features and has a lot of useless cash-grabs too. I prefer the Java Edition but it Microsoft fixes Bedrock, I'd be happily playing on it. :)