HTML is literally only a standard to format data. Nothing else. Can you guys please stop being braindead and do some research? Just because the acronym has language in it, doesn't mean it's a language by any means.
Anyway, aside from that, your end goal is what will make or break your decision. Are you looking to go into game dev or just general software engineering? C++, then, since you'l learn lots more about compsci in general. Are you good at working with data or quickly throwing together prototypes, or maybe you're good at math and want to do data analysis (or big calculations like General Lambert's Problem?) Then Python is what you're going to want to learn.
If you want any elaboration on this stuff, then feel free to ask. But for the love of god, google shit first.