I use alphatrade primarily because about a year ago I did a test on the speed of the quote service. I got three at the same time. One was a firm that is headquartered in NYC, one was the firm I was using, headquartered in Chicago, both were ten times the price of alphatrade. I got the alphatrade account and discovered that the feed was actually FASTER than the one from NYC and only about a tenth of a second behind the Chicago feed - which is amazing since alphatrade is in Vancouver.
Anyway I went with alphatrade to save on the overhead since the speed was no worse than the best feed I could find.
Unfortunately, I've had some trouble two Mondays in a row now.