Although I started with Google Translate on Chrome, I now prefer ImTranslator on Firefox.

All I have to do is Ctrl-C on the text I'm reading and click on the bubble that appears. Google is one of several translations offered. The behaviour is very flexible – there are lots of options.

But for me, the biggest plus is the text-to-speech. The player has a menu option to save as an MP3. On Chrome this is hidden or unavailable. One of several reasons why I now prefer Firefox.