If you're planning to only buy games, Steam is cheaper. If you're planning to rent/buy used/resell games, consoles are cheaper.
With Steam, you purchase a license to play a game. With consoles you own your copy of the game, unless it's a digital copy.
Multiplayer games are less populated on PC, local multiplayer is usually not supported.
Avoid buying older games from Steam, as Steam support doesn't give a damn and they've sold unplayable games in the past, use GOG instead.
EDIT: Forgot to mention that online multiplayer is now a paid service for consoles. Online experience can be much better than on PC but under no circumstances should one assume that this is going to be the case, as it depends on the publisher.
Also I did not assume you were talking about a Wii U since its library is completely different to that of a PC.
"Now go ahead and leap ignorantly to the defense of wealthy game companies who don't know or care about you."
steam itself is all integrated similar to Live or PSN with voice chat, community ect. as well as a lot of other features like workshop which makes it easy to look for mods for games, greenlight which makes it "easier" for devs to get there game available and an entire market place where you can literally buy and sell virtual items youve unlocked through certain steam games (this is how i paid for all my games during steam's summer sale. $67 and i didnt spend a dime). You can now also collect and make badges which upgrade your steam rank making certain things available like a larger friends list and the ability to customize your personal page more. Its like a meta game within the system.
And of course you have the sales. right this very minute there are 70+ games on sale right now, some for 75% off.
However steam isnt the only option for sales. you can also look at Greenmangaming (currently has the entire batman collection for $62 and that includes Origins), Amazon downloads, Gamersgate, GoG(for older titles) and various other retailers. Theres just a lot of options out there for a good deal.
While day 1 sales for new games are pretty rare, you can find a lot of great preorder deals if you want to take advantage of them. The mentioned Batman deal right now, i preordered Bioshock infinite for $45 and it came with Bio 1, 2, Xcom and Civ5(that was an insane deal). i preordered RE6 and it came with RE5 for free and $12 worth of dlc. preordering Tomb Raider came with dlc and a free $15 game ect. all on top of preorders also being cheaper (usually 10% off the base price, but GMG can get as low as 30% off for new stuff which is amazing).
Currently playing: Grand Theft Auto 5 - Shadow Warrior(2013) - State of Decay
Here's the basic pitch on any online service. Certain games you probably want to play will outright require it. Hook, line, sinker.
Doesn't matter what the sales are or aren't, you can find those anywhere and often cheaper or at least equal in price. End of the day though,you're probably going to be activating the same place regardless.