You'll have to weigh up the differences between the two and use the one that appeals to you the most.
There is no 'better' bios, they both basically do the same thing. 5035 gives you the ability to change settings easily by way of the ini file, 4981 doesn't have this feature. Any changes you want to make has to be done through Xbtool and then you have to flash the bios again.
If you have the option to use 5035, I'd use it. Those that TSOP flash 1.2-1.5, you don't have an option as you're stuck with only a 256k bios.
