I have a Central Machinery 10 inch 12 speed drill press with a 5/8 inch keyed chuck. What drill bits are best for mild steel? Maybe this https://drilling-it.com/best-dremel-bit-for-cutting-metal/ ? The speeds are 300-3000 RPM. I have a silver and deming drill bit set from 9/16 to 1 inch, all with 1/2 inch shanks. I run them at 300 RPM with cutting oil and they cut very easily and the motor did not stop. What's best for 1/8 to 1/2 inch? Cheap chinese drill bits burn out very easily and get so hot they oxidize to black. I'm a metal fabricator and I will not even file wood if I don't have to.
High Speed Steel or Carbide bits will work. Pay attention to your speeds and feeds. The smaller the bit, the faster it needs to turn to match the SFM rate. A good lubricant like Cool Tool II works well. Step drilling also helps keep you from burning up even those cheap Chinese bits.
I use moderately-priced HSS drills, but I'm a hobbyist. A couple of sets have Titanium Nitride coating. I've found that my Walker-Turner drill press and small Clausing mill aren't really rigid enough for carbide.
For production use with Central Machinery equipment, you could try a few American-made top-quality HSS drills to see if they deliver enough extra life to justify the price. The bits I buy the most of are #61-80. For them I gave up on low-priced imports 20 years ago.
I recently watched a YouTube video with someone testing about 14 drill bit sets under $40.00. No sets were sponsored. The Black & Decker set was just about even with the Bosch set. The Bosch set being right at the $40 price tag. Both the top sets went through stainless with no problem. Stay away from Harbor Freight for any steel drilling. Hope this helps.