I don't know much about null-space weapons or long-term strategy as I've never used one
but if i may...
Phased polaron beams are pretty much the way to go in early weapons research IMHO, as they can skip shileds and deal a good damage, although you have to get face-to-face to get maximum damage.
Point defense is also something that you should develop early. Or good engines since missles still have ranges.
Torpedo is a heavy weapon that even though short ranged, since they can't be targeted by weapons, ships mostly have to grin and bear it.
Armor is good for early ship defense.
Shields just take to long and by the time you develop PS, others already have better weapons that can pierce right through it.
Engines are a must. Just one PD cannon won't hold up against Planetary defences and missle ships. Unless you plan on building ships solley on Missle defence, you hit, and run, and hit, and run. Good engines will make sure your raider comes out alive.
Missles are only effective early on and in numbers. BIG NUMBERS. Don't expect to live by them for long.
Shiled depleters are useful to boarding ships for independent action or people with creative ideas.
Null space weaponry claim to be a good shot but from what I've seen, they are only good in numbers and escorted. Ships can quickly overwhelm a single NS ship with fast firing weapons such as PPB, APB, and Long range weapons such as WMG and CSM.
Combat support should be also researched but don't make it your priority.
For Specific racial techs,
Crystaline and Organic armor can't be beat but if someone had to choose, OGA should be the first choice as it heals wounds, while crystaline gives off 20 or so shileds, they are quickly overcome and destroyed.
Temporal weapons are... creative. Tachyon cannons don't seem to be worth the effort.
Organic weaponry are not much without support.
Crystaline weapons are nice in early stages, but as shileds develop, they are dead in the water.
Psychic weapons are just not worth it. Alligiance subverter is nice but it misses so many times, even with combat scanners and is ineffective against MC's so...
Religious items are worth the effort, besides the size which makes it not worth investing in small ships but for larger ships invaluable.
There goes my rant