For pen-and-paper games, since fluff is quite mutable in my games, we usually have no problems settling for mechanics first, and adjusting aesthetics to suit the PC. For instance, if a player wanted to play a soulknife, there would be no issues with allowing him to alter the shape of his mindblade into whatever he wanted it to look it, so long as it remained statistically the same.
For PC games, it is a little trickier. But generally, unless the item really looks horrible on the character, I go with functionality over looks. Or maybe looks if the tradeoff in power is small/minimal. But I will likely still keep the backup eq just in case I am not satisfied with my current level of strength.