Short answer: The one you’re most interested in, as that means you’re less likely to give up 😉

If your interest was awakened by the LOTR or Hobbit movies, then you will probably prefer Sindarin, as this is the main form of Elvish used in all of them. Sindarin is also the language used by the elves in Middle-earth in the Third Age.

If you’re more interested in the Silmarillion and ancient times, then Quenya ought to be your first choice. This “Elf-latin” is also the language of magic –  in the movies, for example, the wizards’ spells are in Quenya. 

Speaking of sound and grammar, Sindarin is somewhat similar to Welsh, while Quenya is more like Latin and Finnish. More information is available on Quenya than on Sindarin, as more Tolkien texts in Quenya have been published. 

There are more Elvish languages and dialects than these two, but often a few words are all that is known about them. Extensive information on all Tolkien’s constructed languages can be found on Ardalambion, here: http://folk.uib.no/hnohf/

If you’re interested in studying Quenya or Sindarin, or both, you’re welcome to do that together with us on The Council of Elrond. You’ll find the language Workbooks in the Language section in the main menu.