My two platforms are XBOX Live and Google Play Games.
Believe it or not, I do not own an XBOX console. I have none. So, that is a major limitation (as many of you might feel). I cannot afford to get one. It's too expensive for me and I won't have the time to do all that playing. I have no XBOX 360, XBOX One, XBOX Series S or X. All I have is a PC, and my phones (including a Windows Phone); I even have a controller that has a similar layout like that of an XBOX controller. Of course, WP achievements no longer sync which was a bad move on MS' part; they have nothing really on iOS and Android as it pertains to XBOX Live other than a few casual titles and Minecraft. All others have died except for Halo Spartan Assault (with 5 dead achievements) and Halo Spartan Strike (which seems to work) on iOS. Anyways, I have done some XBOX One titles (just finished Box Align X today) via XBOX Play Anywhere on my PC. In fact, I have done 10 of them. So, that is not so bad. I know. The experience of playing an XBOX console title on the PC (even if a wireless controller is used and the game is projected to the TV) will not match the experience you get when you play an XBOX console game on an actual console. I know. You do not have to tell me. Although, I was close to beginning an XBOX 360 title a few weeks ago. Should have gone ahead and started that. Nevertheless, I did do some GFWL titles.
I know of other platforms, but I prefer XBOX Live. To me, that has games on the most devices (iOS, XBOX, Windows, Android, Kindle and even Nintendo Switch devices) and the achievements are very interesting (such as the "Swept the Ceiling" achievement in Microsoft Minesweeper WP version) and challenging (such as the four time-dependent Jump achievements in Tapping Skill Test on Windows 10). I am sure that Steam and Epic have good achievements too. But I do not have the time to venture there. There is also Retro Achievements for handheld console emulator games. I do not know how those work. I may try some of those at a much later time.
Google Play Games have some achievements that are quite challenging and time consuming. However, some of them such as those in the Parking Puzzle and Knife Crush can be obtained by solely watching ads and mounting up coins as their achievements require you to buy stuff. You do not have to even play the games themselves. Some good achievements are found in Crossy Road, Google Santa Tracker (which requires up to 3 different versions to complete them) and Underway-Tunnel Runner. It's a mix over there but I feel like some achievements were added to games for the sake of adding them. Some developers ditched their achievements. Gameloft dropped theirs for Minion Rush and Wahler Digital ditched theirs on Sinkr. While it's nice to try some titles over there for their achievements, I am not that crazy for them. I cannot speak for achievements offered in the iOS Game Center. I do not own an iPhone.
To conclude, I am OK with XBOX Live and prefer playing there. Achievements are nice and challenging. Google Play Games is a bit OK too. Concerning other platforms, I won't jump into them because I do not have the time to play. I might look into Retro Achievements, but I am unsure of when I'll actually get around to do that.
I play on all platforms. So I have Steam, GOG, Origins, PSN, XBL, Nintendo, and some others. I have a problem with collecting games. I been adding my collection to Backloggery and without adding Twitch, Epic, and GOG games, I'm up to 3500+ games........... I think I have a problem.
I play mostly XBox and PlayStation, but also have Steam if I fancy it. I have a few more consoles like Switch and some retro stuff like Dreamcast or N64, but whenever I play those I'm always thinking "I could be completing Xbox gmaes and earning achievements"