If your really concerned about reliability you need a separate system not needing electricity.  How depends on what you want to accomplish and how.  For instance, a basement might be kept warm with a non-vented propane wall heater, although I would prefer a vented stove of some kind.  I stumbled across this serchin for pictures.  It was designed for a boat and pulls combustin air from outside and is sealed. Very interesting design for a small area. (from http://tinyhouseblog.com/tiny-house/tiny-houses-and-indoor-air-qual...)

It could be set to come on only if it got down to 50 or so. A couple heaters placed strategically in the house might not keep it fully comfortable, but might keep it from freezing during a power failure or furnace break down.

We have a non-vented free standing gas fireplace in our living room similar to this one.

It's an old house and a cold north wind really chills the room. Poor fresh air exchange is not a concern. If it gets too cold the burner turns on.

They make mantles to go around ventless heaters to make them pretty. A friend heats his house with a couple of these

You can get as fancy as you desire.  Backup heat doesn't have to be ugly.

My experiences with high efficiency furnaces is the question is when it will fail, not if.  I was talking with a friend in the propane business last week about an installation in some new construction.  They have the fuel, but someone else got the bid for the furnace.  He said the new furnace (a brand neither of us particularly care for) is being a nightmare because safety controls on the fuel line require more pressure regulation than can be provided.  The furnace requires the pressure be regulated to within 1/10th of an inch water column pressure.  That basically means plus or minus a baby's breath. If the pressure is out of spec (and I guarantee it will be at some point) the furnace shuts down and locks out.

I currently have 2 supplemental heaters, one at each end of the house.  I'm considering adding a third just to guarantee w can keep the house warm if the furnace fails or the electricity goes out.  We were celebrating the anniversary of the blizzard of 1978 this past week.  It kind of brings thoughts like that to mind.

I didn't see enough Trane or Carrier when I was doing service to comment.  My opinion of Goodman was similar to yours, but I am told they have improved.  Bottom on my list was the old Coleman mobile home furnaces.  I remember spending a New Year's Day replacing one because for some reason it had sooted up and there was no way to clean it.  New ones I think have improved as well.

I personally prefer Rheem and Ruud (same furnace, different name).  They are kind of the Chevrolet or Ford of furnaces.  Not fancy, work OK, fixable, good value for the money.  You can spend more, but it isn't really justifiable.

Newer ones with the spark ignitor seem to be less troublesome than the old hot surface ignitors.

OK, off my soap box and back on topic. There are 2 factors (actually maybe more) when discussing why igniters instead of pilot lights.  One is economics.  Let's say you burn 1000 galons of propane a winter.  If you can reduce that 100 gallons (I'm just pulling esy to use numbers for an example.  I don't have a clue what the reduction in actual consumption might be) what is your annual savings? If you are running an old 50% efficient Warm Morning type stove the payback is even faster.

The second is tied to the first.  If you reduced the use you reduce the demand for fuel

Third (I said there mght be more) is a high efficiency furnace scavenges most of the heat from the exhaust which means less global warming.

Fourth is job security.  If I sell you a high efficency furnace I know you are going to need parts.