If the only thing you care about are games, get a PS4. It does nothing but play games.
If you have other needs or interests (like schoolwork, social media, internet, etc) then get a PC.
When trying to guess how long it lasts, it depends on how much you spend on it. Say if you spend $200 on a PS4, games tend to be $10-60 each, and each game generally gives 20-60 hours of entertainment... so it will last as long as you keep buying games. But if you spend $200 on a PC, it'll be a very low end PC that will be absolutely fine for internet, office and schoolwork, but will struggle with games from the beginning. If you stretch your budget into the $400-600 range you'll probably get a system that'll last a few years, and if you stretch even further to the $1000 range it'll last you for several years worth of games. Just remember that whilst you can "obtain" games for free, you'll generally be getting Steam and regularly emptying your wallet into its Steam sales at strategic parts of the year to play all of the amazing (and not so amazing) games in its library.
Because there are a bajillion more games on PC than PS4.