The best replacement for kdm is gdm.

The best alternatives to kdm are rated as following:
★★★★★  gdm
★★★★  hallmark
★★  jdm
★  dkdm
★  lightdm

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

Other search terms related to kdm and their ratings are:
★★★★★ kde
You have in mind a companion for kdm and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of kdm in all years. Click on graph for more.
kdm
gdm
hallmark