I assume this will be for casting? Kind of hard to say on that one. Kings and Cobia are different types of fighters so it may be hard to find a reel and rod setup that will serve both purposes.
But, if you want some just good all around reels, look at shimano speedmasters or tld's on live bait rods. You can literally catch almost anything in the ocean on those things. They are very versatile for a variety of different species. The speedmasters will have a higher gear ratio than the TLDs, however the TLDs will almost have twice as much max drag. Really can't go wrong with either one and they have withstood the test of time. I personally use the TLD 15s and have caught plenty of kings, sailfish, big drum, cobia and all matters of sea creatures with them.
I also have a penn battle 6000 on an ugly stik tiger lite jigging rod that works great for cobia. They have that exact setup for sale at Chasin Tails right now for 170 bucks I believe. That also includes a spool of 65 pound braid.