I tried to translate it a few times but I am still not sure if I am right. The best translation I can come up with is, "Est melior loqui aut mori?" Please help.
You're not far off. You just need to make a few changes:
- Change the masculine/feminine adjective melior to neuter melius.
- Because this is an alternative question – you want to know which of the two courses is better – you need to change aut to an to signal the second alternative. (If you use aut, the question is just a simple 'yes'/'no' question*.)
- You can optionally add utrum at the beginning of the sentence or attach -ne to the end of the first word to signal the first alternative.
- You can optionally tinker with the word order. In some arrangements, you may be able to omit the explicit finite verb (est).
Here are some possibilities:
utrum loqui melius (est) an mori?
estne melius loqui an mori?
loqui melius (est) an mori?
* It's hard to make a good example that works for the English that we're starting with, but imagine that one person says to you, 'Speak or die!' and another says 'Stay silent and be saved!' In this case, you might ask yourself, Estne melius loqui aut mori? 'Is it better to speak or die?' Here, what would be left unexpressed is '...than to stay silent and be saved,' and the expected answer is 'yes' or 'no.' However, once an is used, the question is offering alternatives, and the expected answer will be one or the other of those alternatives, not a simple 'yes'/'no' – even when -ne, which normally forms 'yes'/'no' questions, is attached to the first word. At least this is the rule that the grammar books give (see, for example, Allen and Greenough, New Latin grammar, section 335 – which I actually have bookmarked, because I have to look up this rule anew every single time).