If you are going to buy your chip right now, you will decide by the lakes the chip covers. I have both and like the Lake Master the best, but as others have mentioned, they do not cover TR and LOZ. I go to Stockton a lot and it does cover that lake.
One feature that tips the scales toward Lake Master is the setting for lake level. When the lakes are low, you can adjust the depth settings so you do not get into dangerously shallow water that is normally safe.
Hope this helps