Frankly, no MW is going to be that contemporary looking unless it's an expensive "MW-plus", i.e. like an Advantium built-in ($1700-2700). For the simple MW that you want, look for a countertop MW that will look built-in with an accessory trim kit. I would recommend the Panasonic "Genius Prestige" line. Unlike most MWs that have busy control panels with tiny writing on each button, the Panasonic Genius Prestige MWs have a minimum number of buttons, a clean-looking dial, and a clean and spare control panel. Having said that, some people don't like using the dial, while others do, so that is personal preference.

Note that MWs these days are made with built-in obsolescence; expect a life of 3-5 years, so it's not worth it to spend a lot. I am linking from the Panasonic website which shows MSRP prices. This MW at retail is about $250. You can look up the matching trim kit.

Panasonic Genius Prestige 1200w NN-SD965S

It depends on what you mean by "contemporary". There's a style of interior design called that, or it could be a particular dated design movement, or it could just mean here and now. About half of the microwaves out there fit one or another definition of contemporary.

For your usage, a $100 special from somewhere like Costco would work. For sleek good looks, even though the innards are all made by three companies, you can go way up in budget.

I have some additional questions --

What are those 3 companies and are they the same in efficacy, durability, and functions (microwave, convection, other?) What is worth spending more money for?

Is it worth getting something like an Advantium? (and are people out there happy with it?) since you can spend a lot on labor and parts with a trim kit.... especially if one needs to widen the opening? Does anything really nice come in just 27 inch wide?(in my case, this is to fit an older kitchen remodel.)

Sharp and Panasonic make most of the MW's sold by other makers I think. I'm less sure about the other one. I think it's one of the Korean companies. The guts are pretty similar among all of them. The magnatron degrades over time as part of the way it functions. The wiring, etc., should be fine. The quality of the housing, hinges, buttons, etc., will vary with the badge makers' desires and, possibly, price, though cheap ones seem to be durable. Features also may be spec'd by the badge makers. Company A wants a popcorn button. Company B doesn't want the clutter and prefers an onscreen reminder. Stuff like that. Very few people complain about the function or durability of their microwaves. It's fine to go for looks and budget.

An Advantium is a very expensive machine for making popcorn. It's a speed oven, and unless you need to make a chicken in a fraction of the time, I wouldn't bother for your purposes, since the implication is that you have a real kitchen elsewhere and this is more for snacks. You already said you don't need convection, which is part of what Advantium does. "Speed" is a combination of microwaves, convection and usually some kind of browning element, though some call themselves speed for just the combination of the first two.

As to fitting in your opening, you should be able to find a smaller unit to do that, especially if you can be a little tolerant in the looks department. Most microwaves will fit in your opening, I think, except the ones that are meant to line up with a range (OTR) or stack of ovens. Any decent carpenter or cabinetmaker can trim out your opening to make the MW look nice. Fancy trim kits are only worth it when you're trying to match other ovens.

It isn't cheap ($699), but the ikea NUTID is a very contemporary looking built-in micro, and very attractive imo. Also, you can order it online and don't need to go to the store unlike most Ikea stuff.

http://www.ikea.com/us/en/catalog/products/60288918/

Why not just go with a door lift mech and that way you can have whatever look you want and be free to change your microwave any time you need to.

https://www.kitchenfittingsdirect.com/shop/products?i=114306&c=7102&n=Lift-up-fitting-for-microwave-door

http://www.ebay.co.uk/itm/Kitchen-Microwave-Door-Lift-Up-Hinges-Fitting-500-to-1000mm-Widths-Gas-Cylinder-/261205347825

Blum in the us has lift up mechanisms - I have one in my laundry room for my detergents. Great solution!