Uber & Lyft are about the same. In fact, many drivers drive for both at the same time. The fares are generally within a few cents of each other. There are usually more Uber vehicles available. Some people prefer Lyft because the company has a reputation for treating their drivers better, and they will allow you to add a tip for your driver. You can tip Uber drivers too, but the app doesn't handle it, so it has to be in cash. And there are different promo codes, some giving a free ride up to a certain fare, others giving several dollars discount on a number of rides.
Taxis cost more, often twice as much as Lyft & Uber. A taxi may get you there a few minutes quicker, as there are usually several waiting, whereas you'll usually wait 5-15 minutes for your Lyft/Uber driver. The apps tell you about how long the wait might be before you request the ride.
Also, at DS, taxis pick up at either the West Side or the Marketplace. Lyft & Uber pick up only at the West Side.