The best replacement for pyside is pyqt.

The best alternatives to pyside are rated as following:
★★★★★  pyqt
★★★  wxpython
★★★  pyqt4
★★  kivy
  python pyqt

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

Other search terms related to pyside and their ratings are:
★★★★★ matplotlib
★★★ qt-creator
★ qt designer
You have in mind a companion for pyside and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of pyside in all years. Click on graph for more.
pyside
pyqt
wxpython