Nippon Ichi is the uncrowned king of Srpgs. Nobody can even come close to them.
But, Atlus made Tactics Ogre and Phoenix Wright(which isn't an SRPG but is still like the best game ever)
But then again Phantom Brave & Disgaea are like my favorite games O,o hmmmm
Tactics Ogre was made by Quest. It was just published by Atlus. Sadly, Atlus ussually get's credit for games they simply published.
I also wouldn't call NIS the king of SRPGs. Yeah, sure, they've made alot of good ones recently, bringing SRPGs to the modern gaming audience and to America, where the genre was mostly unknown and unappreciated untill recently. However, I've played quite a few SRPGs and NIS's games are... well, nice, but a bit dissapointing. Disgaea is dull and way too easy, though it's a pretty funny game. Makai Kingdom is far too short. La Pucelle Tactics is VERY easy. The only one I think is a really great game is Phantom Brave. Their games are cute and nice and pretty fun, but there's just not enough content or challenge for an SRPG lover like me. In a sense, NIS's SRPGs are like the Final Fantasy series.