Pet 2 is worth more by a longshot.
Lab rats are unfavourable because of the time and NP to bring the level and def back up, and Pet 2's HSD is higher too.
Don't know prices, but a search or lookup of recent BD pets for sale would give you an initial estimate if you don't want to sit for a PC.
EDIT: Off-topic, but even an even-stat pet that's HSD is half that of a labrat will fetch more.