I agree that Tom's Model Works is probably your best bet for basic PE sets - decent detail, fairly good variety, and not insanely expensive. Good learning tools.
Gold Medal Models sets generally do have a lot more things for each ship, and much better detail (embossed hatches and hose reels for instance) but the trade offs are two - higher cost, and much, much higher frustration level for things like radar antennas and other delicate parts.
What you SHOULD do is compare. Most websites have photos of their PE frets that you can look at and compare to see which one has the most of what you want. I have mixed and matched on both of my ship models to date, and I imagine other modelers do the same.