Our previous homes were old (1926 & 1936) with original wood doors that I painted various colors over the years. They were fraught with issues of weatherstripping that could never be fully remedied but with a new build that's more easily addressed. I agree with jannicone that if your plan is to paint, go with something that's easy to make weather tight and will fluctuate less than wood.

I just don't like the look/feel of fiberglass doors. Yes, wood requires maintenance, but I don't want to live in a plastic house.

I'm going to buy a door from Pirnar.

https://vimeo.com/156805466?ref=em-share

I agree with DLM and Jannicone. If you're painting it, go with fiberglass. Less maintenance hassle and less weatherproofing hassles.

What about steel? Our house came with one, and among the benefits are that I can hang a magnetic hanger on the door to hold decor, as well as stick reminders, tickets, etc on the door.

I've heard that over time the insulation settles in the doors, and they need to be replaced because of that. Is that true?

I would think that any insulated door is done with spray foam that would eliminate any "settling" issue. I am sure steel is fine - possibly more expensive and you won't see the faux woodgrain / harder to paint?

I wanted a painted solid wood door; solid wood doors are not usually built for paint but stain, I'm researching black stain. As an alternative, I received a quote for solid mahogany door covered with marine ply; did not sound too exciting. The 115" x 96" door I had originally planned, included a 6'x8' door with side lites making up desired width but DW rejected the idea of sidelites even if opaque, hence need for a custom door, nothing fancy but a large wide and solid entry door.

The choice of material for an entry door depends on several factors. Maintenance is the highest for wood. And some wood will need a lot more maintenance than others. Wood fades with age/exposure. More sun intensifies that fading. That means more maintenance with UV protective finishes. Weather(rain/snow) means more wear, and more maintenance. Humidity/rain/sun can cause expansion/shrinkage cracks and actual splits in the wood.

Painting a wood door can minimize those problems, but extreme exposure means even painted wood doors will experience problems.

Metal/fiberglas doors can be painted, or even stained. The propensity for weather damage is minimal. Biggest drawback is sunlight can make those door very hot, and warping can occur, which can be intensified when a storm door is used.

For the OP, IMHO, a fiberglas door is the most economical, lowest maintenance choice. Just make sure the door is primed(even with a preprimed model) before painting and a heat escape storm is used(if installed).

For painted exterior (and interior) doors I use TruStile MDF stile & rail doors from Colorado. All the advantages of wood but they are warp resistant. And their web site makes it easy to select a standard door or design a custom door. You can't tell them from a sold wood door.

These doors are what fiberglass doors are trying to mimic but with little success