I like DCC as well on any 7k or larger ship, though if I end up hurting for space I'll toss it.
I never bother with cargo handling higher than the initial tech, for the reasons previously mentioned as well as the fact that at my major colonies I can use spaceports to reduce loading times. I've never been in a situation where I had to have troops dropped off faster, and if I expected to get there I would probably use Combat Drop Modules anyway.
My personal tech priority is Engines, followed by sensors of various types, I find the second level of the survey sensors makes my survey vessels rather a lot faster to operate.
For the production techs I tend to prefer mining over construction rate since any mature colony is likely to have enough construction facilities to build stuff quickly enough anyway, plus I tend to find good Administrators with Construction bonuses. I don't neglect the tech tree entirely, but it is ties for the bottom priority with Shipbuilding. I rate Shipbuilding low as again there are other ways to reduce time, Administrators and prebuilding components come to mind.
For weapons, missiles are king, on a default start I like to learn the 8k level missile techs right away, as well as Box Launchers.
Non-missile weapons come down to Meson Cannons or Railguns usually, with Lasers coming in close behind, I tend to go Energy rather than Railgun as my Kinetic Weapons scientist is usually busy with missile stuff. Lasers have a great range and damage profile, but Mesons ignore armor, and since I usually put them on cheap, small units like FACs, survivability is secondary and they have the speed to get in range anyway.
Depending on your playstyle the Logistics techs can be your best friend. Want to play with Fighters or effective FAC? You need the miniaturization techs from here, period. If you are planning to take anything over via ground assault you need to invest heavily in here as well, and even the most anti ground unit player is going to want at least Engineers and Troop Transports for excavating ruins.
For defense, a few levels of armor is the usual priority as the benefits really pay off in weight savings. Nothing else here is needed though. Bu for midgame I like to put a few layers of shields on all my combatants, even light ones can save a fair bit of repairs simply by preventing the odd leaker that gets through your missile defense.
I tend to ignore ECM/ECCM. While ECM is useful I usually find it to be too big of an investment to care about initially, and later on I can usually make up for it by simply engineering missiles and sensors for longer range than my enemy. ECCM is even easier to avoid, as you can beat enemy ECM by over-engineering your Fire Controls.
I never research the biology techs, finding it more useful to Terraform a world if it doesn't meet my colonization needs. Researching multiple levels of temperature tolerance and so on, then a new species, then building GMCs, then waiting till the numbers are there, then dealing with multiple species seems more trouble than it is worth.
I do like Terraforming tech, the module and tech up to 0.002 are the only investment I really need for it though.
