I've only used XBee, and they're easy to use if you buy the series 1 units. You simply buy a couple
of XBee shields, plug in 2 modules and they will automatically communicate at 9600 bps, without
any setup muckaround [unless something has changed]. To make comms with a PC on one end,
you can buy an XBee carrier board with a USB interface.
This route will probably be a little more expensive than going NRF2401, but I cannot say for sure.
The nice thing is, with the XBee shields, you can also plug in various other modules directly into the
same socket, eg wifi, bluetooth, and others, so you have a lot of options.