A little like asking which is better: Disneyland or Disney World.  Both are great.  Prices fpr activities are the same the Oase is 10 Eur less to enter. I like Oase better in the summer because of its outside facilities (pool, bar, tents, lawn, tree house). In cooler weather I go for Palace which has bigger faciliites inside. Kino at Palace is larger with a better layout letting you see more of the action around you.  Palace is also closer to airport which may be important if you have only one night. Girls are plentiful and wonderful at both. Recommend Angelina at Palace and Linda at Oase.
Both places offer set prices for activities and I have never seen an altercation of any kind in more than a dozen visits. Be aware of  dessous night when they wear lingere.  Other days they are in bithday suits. Dessous tag is Wednesday at Palace.  
I will be at Palace myself this Friday, Oct, 2, and on Wednesday Oct 7 for Oktoberfest party.  Let me know if those dates coincice with yours and I will show you the ropes.  Cheers.