I've done some of the number crunching calculations myself and I think they really show you the best part of the tech/spam balance for the game. I will make this post focused on the techs from TEC as I played them a bit more lately.

There are things that can be valued exactly and things which don't. Those that don't you need to evaluate a rough value or a rough threshold.

About military, mainly ships, you can do these calculations for damage, armor, hull and shield but I think survavability should be the top priority in your list, so shield/armor/hull should be the first to get. It's not a problem that a LRM does 11 damage or 12 damage as long as it lives . The problem is when it dies, as you need to replace it.

I'll take into account only the LRM, which is a nice spam and a very difficult to counter unless you're a pro.
I also suppose you have the labs to get the LRMs in place so I won't count those too. So tier 2 is available.
I take 5 credits as the price for any resource as in most of my games I was buying a lot of resources from the black market and FAST lol

So there are 6 upgrades regarding hull. I will discuss only optimizing the total_hull/cost ratio as this is calculated easily. total_hull means the hull added for all LRMs you have out (built or queued). If you want to do this calculation for HCs you just replace the price of the LRM with the price of the HC and hull values accordingly in the following equations and you're done.

All the rest involving shield mitigation, phase missiles, hull repair rate, fleet slots costs and others are too hard to measure and put into a simple equasion.

1) 1st lvl is +6% to standard hull and costs 400C 25R in short (400credits and 25 resources), assuming 5C for any R, it means a cost of 525 C

a LRM costs 275C and 70R, which means 625C

a LRM has a standard hull of 500. Assuming you have X LRMs out of queued, you're going to have a total hull value of X*500. Now the cost of those LRMs is X*625. so the ratio total_hull/cost is (X * 500)/(X*625) = 500/625 (we'll leave it like this without simplifying it.

Once you have X LRMs built or queued you have the choice of building an additional LRM or upgrading the existing X ones:

- If you build an additional LRM then you have the same ratio 500/625.

- if you do the 1st upgrade of the hull, then the hull of a LRM will be 500+6%*500=500*1.06 will keep this result in mind

the ratio after this 1st hull upgrade changes to (X*500*1.06)/(X*625+525), where 525 is the additional cost of tech-ing

In order to tech up, we need a better ratio, that means that

500/625<(X*500*1.06)/(X*625+525) - this means that we get a better ratio just by upgrading, that means more hull per buck spent. This inequality changes to:

500*(X*625+525)<(X*500*1.06)*625 and this simplifies to 312500*X+262500<331250*X, which simplifies further to 18750*X>262500, which means X>14. So as soon as you have 14 LRMs you can queue the 1st hull upgrade.

2) 2nd hull upgrade costs 500C and 50R and gives a +13% to standard hull, which means it costs 750.

the ratio for the (X+1)th LRM is ((X+1)*500*1.06)/((X+1)*625), so it simplifies to (500*1.06)/625 - I leave out the cost of the 1st upgrade from this as it's not important at this step

the ratio after the upgrade is (X*500*1.13)/(X*625+750). So putting this into the equation, we get:

(X*500*1.13)/(X*625+750)>(500*1.06)/625 - which means we get more hull per buck by upgrading than by building another LRM

this simplifies to X*500*1.13*625>500*1.06*(X*625+750), and this gives 353125*X>331250*X+397500, which gives 21875*X>397500, which gives roughly X>18. So as soon as you have 18 LRMs built and/or queued in total, queue in the 2nd hull upgrade

3) 3rd hull upgrade costs 600C and 150R and gives +19% to standard hull, and means it costs 1350C

the ratio before upgrade is (500*1.13)/625

the ratio after the upgrade is (X*500*1.25)/(X*625+1350)

which gives (X*500*1.19)/(X*625+1350)>(500*1.13)/625, now you've seen the way it's calculated so I'll just put the final result: X>40

4)4th hull upgrade costs 700C and 200R and gives a +25% to standard hull, and means it costs 1700C

the ratio before upgrade is (500*1.19)/625

the ratio after the upgrade is (X*500*1.25)/(X*625+1700)

which gives (X*500*1.25)/(X*625+1700)>(500*1.19)/625 and this simplifies to X>53

5) 5th hull upgrade costs 1000C and 400R and gives a +28% to standard hull, and means it costs 3000 and this does not include the build cost of military labs (it assumes you already have them for the Phase Jump Disruption gadget

the ratio before the upgrade is (500*1.25)/625

the ratio after upgrade is (X*500*1.28)/(X*625+3000) and this simplifies to X>200

6) 6th hull upgrade costs 1100C and 450R and it gives a +30% to standard hull, and it costs 3350

the ratio before the upgrade is (500*1.28)/625

the ratio after upgrade is (X*500*1.3)/(X*625+3350) and this simplifies to X>343

So, these are the numbers. NOW, as this hull increases other hulls too, then this is the threshold you should never pass before upgrading

So, to sum it up, the thresholds are 14,18,40,53,200 and 343. These means if you happen to have more than 14 LRMs and you didn't already upgraded the 1st hull, then something is wrong and so on with the next hull upgrades.

... now shoot, as I have enough hull to withstand your power