Warframe is a beautiful, intriguing, fun game that showcases the proper way to execute f2p. Their f2p model is nothing short of perfection, so well done that I feel joy for supporting DE every time I buy something for/from Warframe. I've essentially quit playing a few months ago, mostly because when I play Warframe, I only want to play Warframe, and my hundreds of other games all get thoroughly neglected. Warframe is full of great content, with more constantly being developed and released.
If I could recommend only one game, it would be Warframe. You don't even need Xbox Live Gold membership to enjoy Warframe (though it's necessary for online coop). They offer us gorgeous graphics and professional quality audio, interesting quests and stories, a veritable plethora of ever-expanding content, and the most fluid, dynamic, exciting and visceral 3rd person combat experience you will find anywhere.
It's impossible to praise Digital Extremes enough for their masterpiece of digital art that is Warframe, but I'm voting Warframe for President 2020 as a write in. There's nothing, no possible reason or justification for you not to try Warframe. Give it a few hours, ask for help when you invariably begin drowning in the almost-too-much content, and once you've done yourself the best favor of your life by starting Warframe, other games will always pale in comparison.