Are we given a heads-up before these superaliens tidally lock our planet?
if we're given a couple of years to prepare, along with knowing where the line will be, that affects where the optimal place for survival would be.
If we get to build a huge solar farm somewhere in the late afternoon or early evening,(it's kinda cool how this scenario turns times-of-day into geographical positions) close enough to night that we could feasibly perform maintenance and transport energy without melting the cables, that could enable us to use artificial lights for foodgrowing in the night.
You'd probably also want to place as many nuclear powerplants as possible in the night, but close to the terminator.
other's have mentioned that you'd probably want to consider water vs land. They probably have a point, but it's not clear to me how exactly that works out. any water in the day will evaporate fairly quickly, and then the seabed will be scorched to a crisp. The vapors will then likely migrate to the night, where they will quickly freeze to ice, resulting in a wall of ice along the terminator.
provided we have some sort of means to generate electricity, this ice is a good source of water, which is good, but I also suspect the ice along the terminator will be quite thick(measured in km, at least), and that much ice can really do a number on any structures in the area.(this is the understatement of the century btw)
It's not impossible that our best bet for survival is actually to just put as many nuclear reactors as possible in the night, and far away from the wall of ice around the terminator. It's easier to heat up a cold place than it is to cool down a hot one.
If we lean into this theory, you absolutely want to put as much forest as possible in the day. If we're all going to live in the cold night forever, greenhouse-gasses are our friends. They wont make the night warm enough to live in on their own, but they certainly wont hurt either! be sure to keep the Arabic firmly in the night, their oil is gonna be very useful too, if we can keep oildrills working in the cold.
I wonder how cold the night would actually get. the atmosphere should carry some heat from day to night, I'm not smart enough to calculate how much exactly, but it would be interesting to know if anything can remain fluid. water will obviously freeze, and so will oil on the surface, but what about oil underground? there's a concept in my native language (swedish) "Tjäldjup", which refers to how deep underground water will freeze in winter in a given location. Where I live it's around half a meter, but further north you can get to almost a couple of meters. In our theoretical night, it would be deeper than any place currently on earth, but geothermal activities will limit the depth at some point. I'm just not sure how deep that'd be.
Perhaps our best bet is to just move into the deepest mines underground, build underground nuclear plants and slowly evolve into moles. Radiation might speed up the process if we're lucky!
Also, we'd better hope the night isn't cold enough to turn oxygen into a liquid, or even worse, a solid. if that happens there's a chance that all available oxygen accumulates in solid form somewhere, and then we're truly screwed!
Of course, if your aliens just want to watch the confusion and starvation of as many people as possible, and they don't find cooked or frozen humans to provide the ultimate quality humor, then N.Virgos answer provides the best gag. That will have the most short-term survivors.