Me 2 cents..My factory SSD, which seems to be a Toshiba hence the 'TS128' designation runs faster than my OWC Mercury Extreme Pro did in my older MBP...but with that said it isn't a fair comparison given different generations of SATA, chip architecture, RAM speed, and SSD integration. It runs faster than the C300 as well. The non factory ones are statistically faster, but how much they will be in real world use is debated. I didn't see anything spectacularly different as a lot of applications simply will not utilize the full capability that the SSD offers.
With that said, it seems the current SSDs in Apples are 1) NOT SATA3, 2) Built off of 32nm technology, and 3) Not rated as fast nor as reliable as other brands. Now with that said, the 32nm Toshiba SSDs aren't bad and while differences now may be moot, in a few years the faster SSDs may be more worthwhile.
If you get a 128 from Apple, you can't beat the price!