There is a reason anti-exploit protection like Malwarebytes Anti-Exploit exist. Use it. Back when HTML5 first came out, it was trash. They refined it enough to beat Flash now however. I remember when YouTube videos used a ton of CPU just to load under HTML5 and Flash was much much lower. Now I use it on YouTube over Flash because that problem no longer exist. Works best on Blink engine. Gecko is pretty close. Adobe Flashplayer might be heavily exploited but they made it run on low resources unlike before. On my computer at least, Flash runs just as low as HTML5. Should at least give them that. Think Mozilla is coming out with a replacement for Flash under it's Gecko engine called Shumway. Don't know how that's going or if it's still being continued. I don't care enough to research it.
As for uninstalling Java or Flash, I won't be doing that for a while. HTML5 isn't making Flash work. As for Java, I play some browser games that require it.