I would be most concerned about performance of the door, firstly. For example, will direct rain or snow hit the door? In which case a solid wood door would have to be refinished more often, plus it might warp or change shape, leading to leaks or making it hard to open/close. A fiberglass door (as much as I always prefer real wood) will have little shape-change and might perform better so far north. Also it depends on how humid the area is and I believe Ontario might be somewhat humid in summer and in winter?

We have extreme temperatures here in central Ontario; most of the time it’s cloudy and 6°C but our summers can be over 30C with humidity and our winters can be colder than 20C below. The door itself is not in any direct sun or snow so I think it will be OK in that regard but I’m not sure how we will feel about the regular maintenance down the road. I am partial to natural wood and I’m always in awe at how beautiful they look and feel but I am concerned about the upkeep. And I certainly don’t want any leaks and cracks over time. I have seen them in show rooms and they’re over 2 inches thick they don’t look like they’re going to split or crack anytime soon. Door sales people are either all the way on one side or all the way on the other making this decision even harder to make.
Fibreglass can look very realistic but are they plasticky?
What are peoples’ thoughts on obscured glass? The appeal of the store is the clarity of the glass and I find ups all upscared glasses distracting.I suppose we could always hang a little pleated French curtain on the inside and use them in the evenings but the thought of drilling into a solid mahogany door is not appealing either. Plus they can look messy. In the style of the house is rustic contemporary.

Whose wood door and whose fiberglass door are you considering? Quality product should rule over the type in your locale in some instances. Meaning a good quality wood door over a crap fiberglass door and vice versa. And very few doors are ever solid wood any longer, they are most always veneer which is another reason for a quality product. Stay away from thee box stores for either.

What are some high end brands I should consider?
I was considering Doorland in Vaughan for the custom solid mahogany door and ThermaTru or Trimlite PlastPro for the fibreglass door.

Not sure where in Ontario you are..but Pollard doors and windows are very good quality. They are located in Burlington