K&B, and Fireball are old standbys.  The Fireballs had some bad seals for many years but the cool plugs took the high nitro and high compression well.  We epoxied the seal before using them.  There are Merlin plugs, O'Donnels, Fox and Rossi, and likely more that are likely OK too. I had bad luck with CS plugs.   Most plugs are long or short.  Since OS came into the picture they make it necessary to take the head off to check for flush in the inside of the head because they are in between the long and short size.  I put 2 washers on the long plugs on the OS motors just to use up my long plugs.  Just pick hot med. or cool for your purposesand most plugs are pretty good.