It depends entirely on whether or not you want them to run to seed. If you don't, it's better to deadhead so that they put all of their efforts into storing up energy into the bulb for next year's display.

We only ever take off the seed head. They were doing just that at Bodnant Gardens last week.

I only take the heads off and leave the stalks.

The stems will make food for the bulbs, too, for as long as they last--they usually shrivel quicker than the leaves.

My neighbours never deadhead their fabulous display of daffs. Never feed them either. Yet for the 23 years I have lived here, they come up reliably and provide everyone with much pleasure. Last year, I was unable to lift a watering can so didn't feed my spring bulbs and I was interested to see how they fared this year. As far as I can tell, they all came up as usual. So did the tulips. Nevertheless, i will be giving them a weak feed this year. Just in case. As per your question, I only take off the seedhead but I recently saw a gardener on the TV taking off the whole stem. It seems anything goes!