Looking for Active Game
Starfinder is worth looking at if you want a Space Opera-type game.
I've found that, as a GM, I have an easier time with posting "frequently" if games have the following characteristics:
- Solo player. They will usually be faster than a group.
- Freeform tendancy. The more rules to the system, the longer it takes to write a post, even if it's pure rp.
- Little worldbuilding. An established world is harder to write for than one that's being imagined with every new line in the game.
That said, I personally am only able to maintain the level of activity you're looking for during very specific weeks of the year. Most other times, I have a specific chunk of 2-4 hours each day set aside for rpol (though it tends to slide around sometimes).
In that time, I make sure all of my players get at least one post out of me. I think I've gone up to 3 posts with one player in that chunk of time with this new system, after which point I tend to burn out.
That said, I'm running something like 10 games and playing in a few. So for me it is actually difficult to have that level of activity for everyone. The way I do my posting has changed to reflect that to be fair to all the characters in all of my games :D
Good luck in finding a game that active though! Your best bet is probably a solo game with a GM that only has a few games running and lots of free time! (The dream :P)
It's back to writing updates for me ;)