What is the smartest buy?

Laz

In terms of rarity and best use of currency, which is a smarter buy?

RandomSithLord

Kyros all day. You need 100 kyrotechs for every 50 finisher salvage. In addition, most new characters require 2-4 crafted kyros.

The usage of kyrotechs easily outpaces the need for finisher pieces.

Lysandrax

The kyros are the better buy because they both have the same drop rate from farming and yet you need more kyros.
Buy kyros and any g12+ that you really need, that is it.