To answer your question they can all be valued here on this thread. Images would need to be provided for all of the remaining card backs in order for them to be valued as already demonstrated.
As you mentioned they can be confusing, certain card back releases combined with which distributor released them and figure combinations can be rarer items therefore in demand more making them more desirable hence potentially greater in value and that is before condition is considered.
The condition will also affect the final price as several things will determine each item in the value.
Many card backs will have the character name plate cut out due to the mail away offers, yours shown are good examples as they all have them intact.
The hanger tabs are more often than not punched through, you will see your Ugnaught still has his intact, that can assist the value in some cases.
The litho or print of the picture of the character will often have a large part missing from when the bubble was torn off similar to you Ugnaught, these are often much worse than that example. Your DSC and Han cards are fantastic examples of a good condition card in respect to the litho.
Then there is standard kids damage like the rip to the hanger of the Rebel Commando, creases and rips, ink damage like ticks marked against each character on the rear or wanted written across the vehicles or figures on the back.
Are the remaining 25 card backs ROTJ cards or do you have any ESB or Star Wars ones?