It depends on what you consider more important for a particular build, they all have distinct benefits and tradeoffs.
For the power plant:
Low Emissions: Really good if you value staying cool above all else for a negligible mass increase.
Armored: Good if your ship already runs cool enough and you want more power for a negligible mass increase, or more integrity in case of mishaps.
For the thrusters:
Dirty Drives: Good if you want to move the fastest and be the hottest in normal space. It runs colder than Clean drives in supercruise, but hotter than stock drives.
Clean Drives: Good if you plan on visiting hot planets near their stars and want to move a bit quicker. It runs the coldest in normal space, but the hottest in supercruise.
^This is a very good summary.
Only two thing to add to the PP discussion:
1) sometimes you can downsize powerplant because you go armored as you get a bit of power output boost from it. Then you actually get weight savings from it. If you do not have the materials for it, level 1 overcharged with thermal paste also gets about the same heat efficiency as normal PP, but 12% more power.
2) I normally go with low emissions myself even that that may end up me needing one size larger PP as there is power output reduction with low emissions PP. I just like the heat efficiency so much. I can scoop between binary stars and not overheat. I can even fly into exclusion zones of stars or many black holes and not suffer heat damage there or when I jump out of there. Low emissions PP makes one pretty immune to heat damage unless one wants to crash into jet cone of a neutron star or something else stupid like that... ;-)
And to the thruster discussion:
There seems to be some confusion with many that clean drives help when scooping, which is absolutely not the case: they consume more energy so they actually harm scooping performance. They are only helpful when in normal space. On the other hand: I have them on some of my explorer builds where I go for minimum heat levels on normal space. But that is mostly for fun really. My DBX runs so cold that I can have its cargo bay full of gold in a haz res and the ships just ignore me as they do not see me at all in their sensors.
For Dolphin, I would definitely give it a shot of having low emissions and clean drives when the planetary conditions are the OPs problem. https://s.orbis.zone/19_n