oh, polish trains site is made by drunk students for a bottle of vodka... It is just terribly bad and haven't changed to the good side since like 10 years. They added some ads though and broke login for me during this time :D If you need to ride using several changes - just don't. You need to book each ticket separately.
German had a lot of useless steps.
Austrian was pretty good, but slooow to open initially. LEO express (Czech, but commercial trains/buses) was pretty ok but sometimes having bugs.
I am kinda surprised how painful the train booking sites could be :D