ImTranslator. It looks fantastic. Regular updates. Very complete. No ads, although it did open a page offering the chance to donate the first time I reopened Chrome after installing. Can donate later if you so choose. The extension I had been using stopped being updated and stopped working properly after a Chrome update way back. Happy to have seen your question. It made me look for a new alternative. Living in France now. Beats the heck out of highlighting/copying text and pasting it into Google Translate.