Labs absolutely have a ton of energy, but in my 20 years experience owning both labs and GSPs, nothing on earth compares to the energy output of a GSP. Obviously every dog has their own unique personality and situation, but my 5 year old lab looks like a senior citizen compared to my GSP. You cant go wrong with either of these breeds, im only bringing up any issues for the first time owner to be aware of. If youre committed to their happiness either breed will be amazing outdoors.
If you want a dog that's a big goofball go lab. I hold my 90lb lab like a baby on his back while im standing up.