conrad says:

It also occurred to me that I never answered in more detail your question as why good is better than bad.

I said it was definitional and that's true. It's true because 'good' and 'bad' are value terms, they refer to what is valuable, specifically, 'good' refers to what is valuable and what ought to be valued whereas 'bad' refers to what should not be valued. Therefore,

If that seems like just some semantic juggling, the only way to not make it seem like that is to actually take a stance on what is valuable and thus give good and bad a bit more cash value.

There are three and only three positions one can take:

1) there are somethings that are of intrinsic value, we call something 'good' if it either is something that has intrinsic value or was act such that it produces more intrinsic value and we call something bad if it either destroys intrinsic value or prevents the formation of intrinsic value.

2) there are intrinsic evils and something is good if it destroys the intrinsic evils or prevents the formation of more intrinsic evils; bad is something that encourages the growth of more intrinsic evil or prevented the destruction of intrinsic evil

3) there are both intrinsic values and intrinsic evils

I think Arthur Schopenhauer may have held--and been to the only one I know of to have ever held-- position (2). Positions (1) and (3) have been held by many though. I heavily lean towards (1).

Of course now one has to define what 'intrinsic value'.

One answer, which I am quite convinced is the right one, is human happiness where happiness is defined as having a virtuous character and pleasurable mental states where by pleasurable I mean every mental state we like: joy, excitement, exhilaration, feelings of familial, friendship, and romantic love, and above all, general tranquility. Virtues are what aide in our attaining and keeping such mental states.

If you ask me 'why are these mental states good? why do they have intrinsic value?' I don't have an answer other than, 'values are what we have to have to live and what make life worth living' which is compatible with other positions besides mine. Explanation has to bottom out somewhere and that somewhere is brute facts about what ultimately is of value.

I hope that's informative.