Fuel Sending Unit better than others??

[WOLFMANmike]

ok so here is a question who makes the best fuel sending unit for the stock tank? im asking because i bought one from Ebay a few years back but it has never read true so here is what it does if i fill up the tank will read half full then as a drive to say a city away it will read full. however once it starts reading full it then starts to drop quite a bit more than what is really in the tank. for instance last time it read on E i only had to put in 8Gallons before it was topped off. so i know the tank is way bigger than 8 Gallons so is there a brand i should be shopping for that will be better for me that will not be 1 extreme to the other?