What are the best alternatives to Google Translate?

This depends entirely on what you want to find out. Here is a list of the websites which I could not have survived my A Level without:

Grammar:
la.conjugaison.nouvelobs.com

Vocabulary: 
www.reverso.net
www.wordreference.com

Other:
bonpatron.com/en/ (Copy and paste, or type, short excerpts into the box and BonPatron will pick up on most grammar/vocab errors and offer alteratives. Not infalliable, but definitely worth trying!)

And if you're looking for something more portable, there are several free conjuation apps available from the App Store! Just give it a quick search and see if there's anything you're interested in. :)