I use both of these services extensively, but have only used Uber (the limousine service), a half dozen times or so.
UberX is at least a 20x, if not 30-40x larger business than Uber proper, which is why they transitioned away from simple black limousine service. A trip to San Francisco by Taxi from Redwood City is about $105. Via Uber it is about $150 (presuming no Surge Pricing) - Lyft/UberX charge me about $40-$55 (depending on wait time). And, unlike a Taxi, I get almost immediate service, by a courteous and professional driver eager for good feedback. As a 15 year+ user of taxis on the peninsula, and having taken Lyft/UberX around 100 times so far - I get a much more enjoyable experience in Lyft/UberX than I ever did in a taxi, some of who did know the area, but many of them just confused new-arrivals to the Bay area in dangerous vehicle that had me fearing for my life.