Always blind research. Hey it's the default rule.
Caveat: I play SMACX. Nowadays always with 7 random factions from the 14, including the one I'm playing. Otherwise after 17 years I'd be pretty bored with the game.

The Caretakers and Usurpers have directed research as a faction power. That's one of the main reasons I play all the other factions with blind research, I don't think everyone should be getting a free faction power. Same thing with getting tech when conquering a base. I don't play with that, because that's Aki Zeta 5's power.
Blind research can be a real PITA to get things done. However it's also a challenge, and I need some of those.
Directed research makes it
trivial to get ahead in the game, IMO. Granted, I'm an almost 17 year exclusively single player gamer. I did have 2 PCs set up for 1 on 1 multiplayer once. Against a friend of mine who wasn't particularly good at the game. He could never do much to me. Neither did we ever really finish the games we started either. I really came to view SMAC as an inappropriate game for multiplayer. Takes way too long.
I've also lately been playing on rather large maps, 256x256. That's a bit of a drag, but as I've not done a lot of it yet, I'm not quite ready to give up on the challenges presented. Sometimes those maps give pathological start conditions though, like 1 square islands, to many factions. Wonder why that happens? Nowadays I'm just restarting if that's the problem.
On these 256x256 maps, I have the foreknowledge that Exploration is going to be really important. In particular, if the default unity supply pod scattering is allowed, scooping artifacts and energy credits from the oceans is enormously profitable. So profitable as to be a crutch. The AI factions don't understand this, so they are at a disadvantage that way. Lately I've started turning off the pods. Haven't played many games of that yet. It makes these huge worlds really, really boring and pointless to explore. I think you could say I've been playing "Pac-Man" in SMACX for a couple of years... now I'm thinking about what the game is, if it isn't "Pac-Man".
One thing I've turned off, is random events. The bad ones are way too obnoxious and painful to put up with. Like you've accumulated 1000+ energy and the market crashes, reducing you to 1/3 of that. I've had that happen even when I had built The Planetary Energy grid. Every single one of my bases has an energy bank, WTF is the problem?? Having research fizzle due to a claimed lack of network nodes is not fun either. The good events don't make up for that kind of punishment. The setting AFAIAC is "do you want some s**t in your SMACX sandwich?" In recent discussion of these un-fun design misfeatures on my
gamedesign-l, someone suggested hey, why don't you just turn that crap off? I said "good idea" and haven't looked back.
Turning random events off, the only thing I really miss are sunspots. They can be useful for pulling distasteful Social Engineering choices, as nobody can bother you for the duration.
I also play with "look first" before settling 1st colony. I think it would be irritating not to find a suitable piece of flat ground. Better yet, pop some pods first, then settle on the nutrients. Or near minerals if I get lucky like that. Minerals = early secret project.
I've played a lot of games with tech stagnation, but eventually decided it didn't add that much to the game, and severely penalized the AI players.
Abundant native life seems to really penalize AI players so I don't do that. I've seen games where most factions are Dead On Arrival. Presumed wiped out by stupid choices regarding mindworms. I've decided to just start over if I see that sort of thing happening again.
So now you know my assumptions.
Oh and always Transcend. On 30%..50% land worlds. Which seem to yield a surprising number of water worlds with island archipelagos.