Typically here in Tucson, Bob's flour is 1.5 to 2 dollars per 5Lb. more than KA. That is comparing AP to AP or KA Bread flour to Bob's Artisan as I've never seen Bob have a bread flour.
Hypothetically, if both brands were the same price, would one be better over the other and worth the extra cash??
Personally, for AP or bread flour, if I had the two side-by-side and one was a couple bucks cheaper than the other, I'd likely buy the cheaper one.
At least in Western Canada, Bob's flours and grains are a lot easier to find than King Arthur's. Honestly I'm not sure they distribute here, though it is easy enough to find their flour over the border in Washington.
Here's something on point:
https://northwestsourdough.com/bobs-red-mill-vs-gold-medal-and-king-arthur/
Any wheat flour will work - if you are used to it. If something is worth the money is up to you. Hey - if you like it - the cost is minimal. Enjoy!