The best replacement for xbee is zigbee.

The best alternatives to xbee are rated as following:
★★★★★  zigbee
★★  nrf24l01
★★  xbee pro
★★  rfbee
★★  3dr
★★  nordic
★  wifly
★  xrf
★  bluetooth arduino
  wixel
  apc220

Your alternative for xbee is not listed? Suggest!
Speaking about xbee, one probably shouldn't forget about arduino.

Other search terms related to xbee and their ratings are:
★★★★★ arduino
★★ msp430
★★ arduino mega
★★ arduino micro
★★ pic16f877a
★★ arduino uno
★ labview
★ beaglebone black
atmega16
You have in mind a companion for xbee and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of xbee in all years. Click on graph for more.
xbee
zigbee
nrf24l01