After having spoken with a few people, It seems that there are still many infinity players that are stuck in the "best unit" mindset. the problem with the idea is that there isn't one in infinity. At best, there are units that are far easier to use effectively than others, but they usually have some form of restriction, either points, swc, availability, not being in your sectorial list, or a combination each. Then you have the problem where even a lowly caledonian volunteer with a rifle can lay waste, since you can bypass armour on a crit. To really look at which units give you the most bang for your buck, you have to not only factor their stats, but also their equipment, and how their equipment interacts with their stats. then you have to look at how that interacts with your playstyle. then you have to look at how much they cost, in both points and swc, and look at whether or not you can get an equivalent performance from something else.
Even with that analysis, because infinity is a very complex game, and is played on terrain boards that are very dense, all that analysis will give you is a rough approximation of what you can expect from the unit. adding in factors like your skill at maneuver, and your opponent makes it near impossible to have an accurate gauge of what is best.
That all having been said, I say take what you like, and practice with it until you are good at using it.