I just got ads on twitch, but like others have said Twitch has been working HARD at plugging ad blocking methods. Sometimes they will plug a new blocking method people find in less than 24 hours. They are very serious about trying to stop it.
Like Boo Berry said, with the amount of work Twitch is putting in to stopping ad blocking it will only be a matter of time before the only way you're getting ad free twitch is either by subscribing to the channel or subscribing to twitch prime.
For the time being however I have found a Chrome (I'm using it on Edge just fine) extension (also available for Firefox). So far after 3 days use, I haven't seen a single ad. But that could change any day now.
Also, this page I found pretty handy. It's kept up to date with info on different twitch ad blocking methods and how effective they are at the moment. The U-block Origin user script method on that page worked great when I tried it on Firefox (Before TTV LOL was restored to the Firefox extensions store).
Edit: The Firefox version of the TTV LOL extension is back up on Firefox's extension store. The developer said it was removed for " synchronous web requests being made". They submitted a fix, and it just went back up a few mins ago.