The free parking win all money on the board gives everyone a comeback chance

The big problem with that rule, and it is a common theme in most house rules, and in many games other than Monopoly is that it puts back into play money that should have been destroyed.

Games have a fine tuned balance between resource sinks and sources, if you break the balance, for example by removing a sink, as it is the case here, you break the game. Here it tends to result in much longer and boring games.

Plus, it is a poor comeback mechanism. If you don't have property, cash alone is not enough to get you back into the game. Monopoly already has a limited but better designed comeback mechanism with "repair" cards.

Curious to know what are your rules modifications.

By terrible house rules I mean things like collecting money on "free parking", limiting trade or not auctioning unbought property.

I have yet to see commonly practiced house rules that improve the game. I am sure there are, but most people who know enough about game design to actually improve on the game typically don't play Monopoly.

Removing the monopoly requirement for building.