I always think that a mid-tone natural wood colour is the best option for staying power. Right now I like plank width of 4-6". That being said, a lot depends on the style of the house. In a 1950's era building 3" wide oak would be appropriate. In a building from the 1800s much wider, silvery grey oak would be amazing. We had a room in our previous home that was 15x25' and the floor was natural doug fir, 8" wide boards that spanned the entire width of the room, so every board was 15' long. It looked fantastic and was the first thing new visitors commented on.

@AB...Montreal (heck Quebec in general) is big enough with a large enough population to sustain quality mills. It's just a matter of finding them. And yes, there are industry standards or "Best Practices" that can hold up in court (I'm in Vancouver which means I have a little bit of understanding of the Canadian market). As for the mill that will do this...that's the tricky bit. If this were my project (as a newbie homeowner in Montreal) I would find the OLDEST wood flooring company (family owned and operated since "XYZ") in a 50km radius. I would then stop by with some photos of your home (smart phones are SOOOOO handy) and ask if THEY know of any supplier that can get the 1.5" width for you. I will bet dollars to doughnuts (TimBits anyone?) they will have the ability to find whatever you need. If they've been in business for 25 years or more, they will have run into your floor width DOZENS (if not hundreds) of times and will have sourced more of the same. But before you go racing off, the next thing you will do is MEASURE the amount of "meat" on your floor. That is the amount of wood sitting ABOVE the tongue. You will find a cross section of the wood (floor vents are AWESOME for this) and measure the thickness sitting ABOVE the tongue. You MUST HAVE 3mm or more to get another sand/refinish out of this floor. That will tell you how much effort you need to put into finding a match. If your existing floors are "lifeless" (no more wood left over to get another refinish done) then "matching" doesn't make sense. You would be matching to something that has very little time left on earth...and once it 'dies' you will then be faced with matching the NEW material that was matched to the OLD material...and the whole thing starts again. If it were my project and there was NO LIFE LEFT on the original floors, I would go ahead and bring in the more common 2.25" planks knowing that in the future, when the old wood is finally gone, you will be matching a more modern strip flooring which is much easier to find (no need to make special inquiries). If there is plenty of life left on the floors, I would track down the "old timer" who's been selling floors for a 'coon's age and find out how to source the 1.5" planks. It is well worth the effort.

Thanks for the additional photos. I think the stain on the current floor, or slightly lighter than the one with the tag are good choices. (Make sure they're installed the long direction as with the current floor to add length to the room.) If you're finding the room is too dark, then repaint the walls a much, much lighter, shade that works well with the current wood cabinets. The dark gray walls, plus all the dark furniture, is weighing down the room. Your cabinets look fine. Look how light and bright this kitchen looks with light gold flooring and pale gray walls.

The OP mentioned that the 12' width and the 15' width are the same price per yard. I don't quite understand why the difference is several hundred dollars, as you are probably only talking three or four square yards difference, but I do understand that 12' is less carpet and therefore cheaper. So if your carpet is running near $100 per yard, then that could easily get to a $400 difference and while that is high, it is not unheard of. I also suspect that the installers are independent contractors who get paid by the square yard of carpet, so the carpet seller doesn't care how much more labor is involved in an install because they have to pay the installer the same amount regardless of whether or not it is an easy install. --- As for the other options. There are several options other than carpet for a basement floor. I personally don't like engineered flooring over concrete, it is too hard to be comfortable to walk on in my opinion. If the ceiling is tall and the space is not finished currently, I would install sleepers, which raise the floor 2" but give it some bounce. There are some good LVP products that are easier to care for than carpet and have a decent feel when walking on them. I have Flooret installed over concrete and it is comfortable to walk on.