both are very reliable. usb3 is alot faster than esata. eSATA can handle 300 MBps (MegaBytes per second) and USB 3.0 can wheel and deal up to 625 MBps.
Basicly, usb3 will co as fast as your hd can w/r. i get 100 megabytes/s on my laptop.
usb3 can have longer cable lengths.
usb3 gives out more power (read: faster charge times on devices that can support it)