I played on steam, battle.net, PSN, Dreamarena and Xbox Live. Xbox Live is by FAR the best service on the market.
The UI and integration of all the apps works just perfectly fine. Better than anywhere else. The content is awesome, the online gameplay works easily, same for the cloud storage, cross game chat, perfect customer service (something PC gamers don't even know in this form), integration with PCs is already pretty good and smartglass will be another step in the right direction.
XBLA > every online-game-service on the market.
Steam has good deals from time to time, but is full with cheaters. CSS, CS 1.6 is nearly unplayable. It doesn't feel like a community at all. Account-hacking is pretty bad, too.
Battle.net is full with hackers as well. 2 out of 5 games on WC3 (I still love that game) is against someone using MH.
PSN has a crappy UI, less content, fewer apps, no cross game chat at all, but more updates which take forever to download. Not everybody has a headset.
Sure you pay for XBL, but it is worth it. I am a XBL gold-member for 8 or 9 years and I don't regret a single day.
Imagine not having GamePass on your console...
