I am quite certain this gives accurate guidance on the impact of how spending stat points will impact your average attack.
I won't go into detail on magic and mounts and legion damage and all that stuff, but suffice it to say that this is very well researched and if you want to do maximum damage use this guide.
You have to calculate your crit. The game gives a 2% base crit chance and then your gear and legion add to it. Depending on what you're using and what you're hitting it can change. You will find though that you can run the numbers with different crits and largely the guidance is the same