This is my favorite choice. You will need 3 purple augments, but it wastes very little, leaving 10 gear slots and 8 augment slots to maximize your critical stat.

This is another good choice, although most people prefer Option #1, which uses the Advanced Proficient Kyrprax Stim. This gives Option #1 394 more critical rating, but this option gives you an extra 264 Mastery and 109 Power through the use of the Advanced Versatile Kyrprax Stim.

If you find the cost of purple augments prohibitive, this may be your best option. Remember though, what you don't spend on purple augments, you will still have to spend some to buy an extra blue augment. As you can see, you waste a lot more Accuracy and Alacrity that don't give you anything and lose some Critical Rating, but not too much. 

Similar to Options 3 and 4, taking this route allows you a little extra Mastery and Power, at the cost of some Critical Rating. The differences are exactly the same as in Options 3 and 4, so it's up to you to decide which is the better option.