I have quite the collection of needles, over my years of knitting. I have a few straights left... I never use them. I mainly use circulars and DPNs as I love knitting in the round.
I will tell you this, I used a circular set of size 10, 36" for years when I was just making afghans and the odd "square" project. If that is your main goal, at this point in your hobby, then you can't go wrong using 10s with a 4 or 5 weight acrylic yarn.
When you find something you want to make that requires a different size, buy a cheap set. If you continue working, then buying the KnitPicks Options or AddiClicks would serve you well. I'm still waiting for mine. I have the ordering information on the fridge, inside pantry doors, pasted on the mirror in the bathroom, and in the center credenza in my husband's truck. If I have to buy my own, heads will roll, which means less hat making for me in the winter.