Fixing airplanes in the Navy I can guarantee you I get crappier drill bits than thou. A common one in our system is Huot, which is actually an okay drill bit. Everyone accuses them of being crap because they misuse them. HSS means they are made from tool steel, not for drilling steel. Works great on aluminum, brass, other non-ferrous, etc. Cobalt also refers to the material of the drill, still a high carbon steel, I don't know the alloy specs. Makes no difference to the user. Cobalt for steel or CRES(stainless). Ti nitride is as noted a surface treatment, rendered the surface .001-.002" harder than woodpecker lips(Similar, but not the same to Glock "tennifer"). Once you kill the surface coating, it is like any other drill bit. The big difference to the user between cobalt and HSS is not material, but the tip angle. Compare a HSS bit to a cobalt and you will see the cobalt has a flatter point with a back cut into the trailing edge of the cutting face. That is what makes it superior to an HSS bit on steel.
Now the best bit in the world can succumb to the misuser, as can a properly used dime store bit last a long time, it is correct drilling practice. If you are breaking lots of bits, you are applying too much pressure, let the drill do the work. A lot of bits get broken right at break through on the back side of the material when the drill bit hangs, the best thing to do is ease up on the speed and pressure when you feel break through coming. speaking of speeds and feeds, Whatever the drill bit will bear and high speed in aluminum and other soft metals. Make chips fly. Use lube. Ease up on thin materials so you don't break what you are "fixing". Steel, medium heavy feed, SLOW speed, oil! CRES, same deal. Stainless is the most unforgiving of metals for uneducated drillers, many of the common flavors work harden, so the instant that bit spins without pulling a chip excess heat is generated, the metal work hardens and in extreme cases of no trigger control you see the bit tip turn red. You are left with no hole and a very nice fluted, annealed, Q-tip. Again with stainless, slow speed, use lube. Keep the work and bit cool. Many soft metals will turn a continuous curly chip. That is a pretty good indication of proper feed pressure.
On specific bits, if you use a lot get an industrial supply catalog and buy the right sizes in bulk. MSC Mach. Supply Corp. is a good one. I thought Bullet bits were a gimmick, but my dad and I have used one set for ten years, they are still going strong, we do plenty of drilling.
