I think the lamp would be best. Heating pads can get really really hot if they're unregulated, so if the snake burrows underneath the substrate, it can get burned. You should also get a digital thermometer with a probe to measure ambient and hotspot temperatures when you're using heating equipment.
Really, I'm not sure you need either of them. I don't know how warm the room where the snake is kept gets, but I've kept my corn snake with no supplemental heat for the past seven years and I've had no problems.[/quote
I agree, well said. Especially about the heat pad. DON'T use it. One of my snakes died a few months ago as a result of burns caused by a heat pad.
Snakes are stubborn especially ball pythons. My ball python laid on the heat pad until its belly turned red and eventually became an open sore.