
Hi Layla,
I think it comes down to preference really.
My preference for various reasons is the heat pad, you can get the pups on the heat as soon as they are born ( of course after drying them etc) . The pups can move on and off the heat pad very easily. I always have a thick bit of vet bed over mine rather than than a thinner bit and have found this to be the best way. I put the heat pad at one side of the box and the mother can go to the opposite side away from the heat if she likes.
I bought and tried the heat lamp recently as a freind favored that method but I only used it for a day and went back to my heat pad. The heat lamp is or would be good for keeping a room a bit warmer or a puppy run etc
The other thing a heat pad is excellent for is if you bitch needed a section etc as they need to be kept warm afterwards and the heat pad underneath them I think get the heat in their body quicker.