I mean, it's all personal preference.
I say boy but I'm biased
I was raised with girl dogs my whole life. The best girl dog we had was our Golden Retriever, Daisy. The others were all like human females - bitches! LOL. They get moody and alot more nippy and agressive around certain bones, etc. Whereas I've never had any of these moody problems with Jackson. He's SUCH a little boy! However, boys are a lot more needy and require more attention, I think. From what I've gathered on this website and others, males tend to cling to female owners more and female dogs cling to male owners more. Males also seem easier to train. But again, none of this is ALWAYS true.