Your cost for 1000000 btus on propane will be $45.63
For the same energy w resistance heating $32.24
For the same energy w an air to air heatpump with a COP of 2 $16.12
If you go all electric a lot of the electric companies will give you lower electric rates for the winter season which may help even more. Also check for rebates BEFORE you buy anything as they may have specific requirements you will have to meet.
I'm changing my own house over from propane to electric, so all I had to do was plug in the numbers in the spreadsheet I already created. I have a 3200 sq ft home and will save about $2000 per year. This is enough to justify the air to air heatpump, but not a geothermal, mostly because I can get a $.04/KW rate for the winter heating season from my utility.