I need to get a new countersink bit, one that will last & stay sharp, which I use mostly for when I re-bed deck hardware and apply fasteners ... I chamfer the gel-coat slightly for a nice saddle of sealant and to help prevent the gel-coat from spider cracking / crazing. Occasionally I will use it for wood & flat head fasteners. Am wondering what the best size, style would be if I want to get only one, a universal. Looking at McMaster-Carr, there's all kinds of 'em. I'm thinking 5/8", 82 degree, 3 flute. Is Colbalt a good idea ?

Wondering if anyone has a specific suggestion what works for them ?

Thanks, cheers, John