I've been using UberX, the cheaper, non-limo version of Uber. While the availability of the UberX cars are not significantly better than regular taxi, it is significantly cheaper than one if you take it during peak hours and after midnight, as they do not have peak-hour and location surcharge and though their per-km rate is slightly higher, the total cost is actually cheaper than regular cabs.
UberX was the first to provide driver's mobile number so that you could contact directly. After that, Comfort Delgro and SMRT followed suit.
So I use UberX during hard-to-get-a-regular-taxi hours like shift-change, rainy days, airport runs and after midnight.
UberX account is linked to your credit card and your receipt is emailed to you after each ride. Your fare is quoted on estimated basis before you choose to accept the ride (you can even view where your potential drivers are before you book) and it is finalised after the ride. And it can submit ride summary if you intend to submit for claim from your company.
If anyone is interested, here's my invitation code 9r4sd.