Let me preface this post by saying this is the weakest generation since the NES/Master System days. Even though I was born at the tail end of the SNES/Genesis era, I experienced those games through various ports and remakes, especially on GBA, and I feel that from the fourth generation to the end of the seventh we were spoiled by a plethora of amazing games, including many great new IPs. This generation, on the other hand, has been a dumpster fire of sameness and safety. Although not home consoles, I feel like games on the 3DS and PS Vita took more risks in creating something new. That said, I have hope for the future with new IPs from Sony and Nintendo like Horizon: Zero Dawn and Arms, respectively, as well as supporting newer franchises with sequels like Gravity Rush 2 and Splatoon 2.
Right now, I have to give the edge to the PS4. Like others have said, there is the biggest variety of great games available on the system. Its 2013 launch and 2014 were slow, but ever since 2015's Bloodhorne, the PS4 has been killing it. My only gripe with Sony is how they frontloaded this year. It was pretty clearly to compete with the Switch launch and while Gravity Rush 2, Nioh, Horizon: Zero Dawn, and Persona 5 headlined a strong first four months of the year for PS4, I feel holiday momentum has whimpered out. Knack 2, Gran Turismo Sport, and exclusive content for Call of Duty: WWII and Star Wars Battlefront II can only take you so far during the holidays. The PS4 is definitely the safest bet for future content with how well Sony supports their platforms, but I don't think it's the place to play the hot games this holiday.
Jumping onto the Switch, I think the system has had one of the best launch years ever. It can be debated whether the SNES or PS2 had better launches, but the Switch is up there. Breath of the Wild and Super Mario Odyssey are arguably the two best games of the year. The only game that can compete with their quality on other platforms is Persona 5. Nintendo has also done a much better job of building an online community with Mario Kart 8 Deluxe, Arms, and Splatoon 2 out within the first few months of the system. It's hard to deny that the Switch is the best place to play this Christmas, but the future remains uncertain. I'm sure Pokemon and Metroid Prime 4 will headline a great 2019, but I hope Nintendo has some big hitters planned for next year. Fire Emblem is getting more popular these days, but Animal Crossing would do a lot to bolster the system's popularity next year.
It's with great shame that I declare the Xbox One the worst system of the generation. The only reason to own one is if you're a diehard Halo, Gears, or Forza. I say it's such a shame because the Xbox 360 was my favorite console last generation, and I still think Xbox Live offers the best console online, but there are just too few exclusives available for the Xbox One. Microsoft barely puts out content from January-August so they can focus on fall and holiday releases, yet even then, there are slim pickings. There are no great new IPs being created anymore. Cuphead is probably the best reason to pick up an Xbox One this year, but almost everyone will choose to buy it on PC instead.