I've had both BSL and ISA browns. Wonderful producers of big brown eggs. But for my 2 cents, I'll pass on the ISA browns. I found them to be aloof and unfriendly in a mixed flock. The BSLs are great egg machines and they are quite friendly and easily handled. I also think that the BSLs are prettier than the ISAs. I think that they are better as a dual-purpose bird as they are bigger than the ISAs.For years I have maintained a rainbow flock of laying breeds but last February decided to replace the entire flock. I initially was going to purchase just ISA browns but opted to also purchase some black sex links and I glad that I did. They are an attractive breed and lay extremely well. Since I wanted to keep my total bird numbers down I only purchased 8 ISAs and 6 BSL. Those 14 birds have given me 460 eggs since January 1st and all have been predominately extra large and jumbos. For someone just getting into chickens and wanting calm thrifty high egg production birds I suggest you consider them.
It's nice that there are so many breeds available to suit ones particular needs.
I guess I've been lucky. Then again, I do get around to different areas. Sometimes I just get lucky, like with the BAs.They are really cute! Where do you find these awesome birds? Our pet stores around here only sell fish.