The definitive answer to that question is - it depends.
Many modelers use different pieces from different photoetch frets during the assembly. What it comes down to is two things - how much $$$$$ you're willing to spend, and which set has the most stuff that you are actually likely to use. As I suspect you are already sensing, it is very, very easy to go too far down the photoetch road and end up spending all your time folding itty bitty bits of metal instead of enjoying your build.
I'm not a battleship guy, but have personal experience with Gold Medal Models PE, and it is some of the best in terms of both fit and (more importantly) clear and concise instructions. Other good sources you may want to check out are Toms Model Works and White Ensign Models. Both have 1/350 Iowa-class battleship PE sets.