A reliable alternative to Selenium and iMacros?

Question

Browsers

There is a task to periodically place / raise ads on a dozen specialized resources using a simple script and a browser plugin. For this purpose, the Selenium plugin for Firefox is used, which turned out to be a glitch. Sometimes, out of the blue, he doesn’t see the button, although it’s definitely there and finds it with step-by-step debugging, and at startup - only in the mood.
Plus, the amazing inflexibility of the API, even if you do not write a sequence of clicks with an inline script, but muddle the code in Java. For example, sending a non-letter button press (tab) is a universal problem and a cloud of posts on stackoverflow.
I also tried iMacros earlier, but it was buggy in various and hopeless ways.
Who knows working, reliable alternatives to drive and not repair / understand?