For skilled players
going for rapid growth/ease of advancement I'd rank the tree power from best to worst as: Combat > Industry > Leadership ~ Tech.
The Leadership/Tech tie just depends on personal preference: Leadership has better fleet boosts and fighters, Tech has better player ship combat boosts and navigation. Both have a few skills that are powerful enough that they will have 3 aptitude ranks. The only tree I refuse to not take is Combat. I've done challenge runs ignoring 1 or 2 trees, and as long as I have Combat things are going to be ok/fun.
The reason for the high Industry ranking is that the only difficult part of the game is early game, and recovery/D mod mitigation/loot booster skills make the early/mid game much easier. As a specific trick, Converted Hangar + D mod reduction is
very powerful.
I think industry tree is clearly the tree that is worst for a skilled player and best for a neewb. Many of the skills depend on you losing ships to get value, so if you're playing perfectly and never losing anything, you don't get much out of those skills.
...
If you take Industry, playing perfectly no longer means losing no ships. Since ships return with low to no D mods and the recovery rate of high quality enemy ships is so high, its more efficient to fight larger enemies, lose ships, but recover more and better ships in the process, thus snowballing upwards. The presence of the skills shifts the cost/benefit analysis of combat.
As an example, in a normal run I would never attack a Persean League patrol thats bigger than me with no commission/bounty, as profit is only medium, but the chance of losing a ship and at best getting multiple full strength D mods is too punishing.
With Industry, I get enough loot to justify the attack by itself, the risk of losing a ship suddenly doesn't matter nearly as much, and the value of recovered ships skyrockets. Just today I attacked a patrol: I lost a Wolf (recovered with 50% structural), a Shepherd (Recovered with 50% glitched sensors added), but gained a Tempest (0 D mods), 2 Drovers (50% Structural on 1, Increased Maintenance* and 50% Sensors on the other), and a Hammerhead (50% Armor D). That kind of early game growth just isn't possible with other builds.
*Increased Maintenance actually lowers operating costs if fighting more than once every month or so.
Once a player is done with the growth phase and not adding new ships, Industry skills lose some value. But at least to my mind, once the player is done with the growth phase the game is over because every fight is trivial, so I don't care. I think people who enjoy playing with their 'endgame' fleet won't agree with the industry ranking, as its being judged by a different metric.