Account Compromising CONSTANTLY on games that have their own client

And what's weird is that my account has NEVER been compromised on LoL.

But my account has been compromised on Ubisoft Client & Runescape client. Like, constantly.

-Virus scans done -Malware scans done -Computer is completely secure -Never do online transaction in wifi space that isn't my own or neighbors

So, why exactly is LoL, a free game, so much better at securing data in comparison to the others? This happens a couple of times a year, more times than that for Runescape. I just don't even touch Runescape because they go by a guilty until proven innocent method of ruling. (Hah! You spent 10 bucks on a membership? Eat shit, kid, you're gonna have to wait 2 weeks of guilt riddled forums until our support can save you! Enjoy the remaining 5 bucks membership on your account, kiddo.)

In all seriousness, I'd like to believe that my LoL account is a lot more worth while than the other accounts. So what's the big deal?