Insulation almost always wins during initial construction.
Solar panels probably come in second because they create waste energy that unlocks free EV charging, etc, etc (but you will pay more than $10K for the system), so, thanks to sunk costs, other stuff becomes "free".
Heat pumps are probably the cheapest big bang for the buck upgrade for existing construction (especially if you have to replace your HVAC anyway). Minisplits are often a big win for retrofits of buildings without central air.
All of these things are dominated by labor costs, and we are in the middle of a labor shortage. You are unlikely to find realistic financials unless you get bids and compare with your personal energy rates.
We didn't do any of that.
We just assumed energy prices would continue to explode over time (we were right), and jumped off the inflation carousel by putting in solar and all electric appliances.
Also, we can't get natural gas service, and propane costs 4x per BTU more than natural gas around here. Most electrical appliance upgrades are subsided by the government to make them competitive with natural gas.
That made it a no brainer.
Since then, a bunch of indoor air pollution research showed that natural gas causes asthma, etc, etc. Also, the war in Ukraine started.
So, what are your health, future financial predictability, and engineering economics braincells worth? For us, the answer was "less than the installation cost of the system".
Also, after all they put us through, seeing a -$120 bill from PG&E each month makes me irrationally unhappy. ;-)