First letter of a language name

First letter of a language name
 

In English, when you write language names, the first character will always be in upper case. I want to know, is it a good idea to make the first character of a language name to be in upper case in Spanish?

Following is an example, these words are shown on a web page for visitors to choose their native language.

Arabic
English
French
Italian
Russian
Spanish

After translated into Spanish, there are following two choices.

Arabe
Inglés
Francés
Italiano
Ruso
Español

or

árabe
Inglés
francés
italiano
ruso
español


Which is better? Thanks for help!

In Spanish, language names are not capitalized unless they are the first word. This is usually interpreted to mean the first word of a sentence.

When listed as you have done, one word per line, I've seen cases when the initial letter is capitalized because it is the first (only) word.