Thanks for all the comments, everyone. I was offline yesterday. That pic of the HR-V vs CX-3 is a very helpful visual, too! Thanks, DKaz.
Again, it's always just me in the car. I care more about my own comfort and driving experience than anything else.
Frau, I love driving the CX-3. If you get it in GT trim, the headlights are superb!!
... But it becomes difficult to live with in terms of no arm rest and thick A-pillars.
If it's just you, there is plenty of space in there so long as you're not looking to store tall items that you can't lay down, or large cubes.
Fuel economy in the city is spectacular - mid 8's usually.
Highway isn't great - usually low 8's. If you do a ton of Highway, is something to consider - as is the oil change interval.
The CX-5 manages better Highway fuel economy FWIW I'm real life.