As others have said, Steam is the way to go for PC gaming. Regular sales and/or discounted prices, and a nice repository for all of your owned titles.
Console gaming on 3 Mbps internet is....iffy, at best. I know, I've been there. It was the only speed available at our new house until about 4 months ago. And as Lenas said, playing a console game the day of release was just not happening. Most games had a 4 - 8 Gb patch on day one, so that meant I spent the entire first day downloading instead of playing. However, if you are more interested in older, single player titles, then console can be very convenient.
Sam wrote:
I see a copy of say, Skyrim, on Amazon for sale but it appears that it may just be some game code? Does this mean I need to use something like Steam to play games at this point? If so, is it worth my effort given my internet speed and download restrictions (I don't even know what that is tbh...maybe 150gb/mo.?)
It depends on the game title, but usually those codes will be redeemed through Steam (or Origin, EA's 'steam-like' service). Very rarely, you'll come across one that you can download directly from Amazon, but that was mostly older titles.
IIRC, the base install / download size of Skyrim (Regular edition, not the new Special Edition) was around 9 GB, so you can set it to download overnight, and play the next day.
Just be mindful of your data cap. With game downloads and Netflix streaming, you could bump up against the cap fairly quick.
The nice thing about Steam (and since you mentioned Skyrim) is that you can 'subscribe' to Steam workshops and mods for Skyrim, and Steam will keep these mods updated for you, automatically.
And I'm sure others will agree, but you definitely should give Skyrim a try. If you can snag the Legendary Edition (which includes all the DLC's) for a good price, then jump on it. That game and all of the DLC's will keep you occupied for quite some time.
As for Witcher 3, I can't really comment, as I haven't played it. I own both Witcher and Witcher 2 and I just never could get into the playstyle. Just never kept my interest, so I didn't bother picking up Witcher 3. That's not to say you wouldn't like it, though.