For general purpose drilling, I'll normally get Cobalt drills. More durable than pure HSS, but typically slightly more brittle (not as brittle as pure carbide though!), and can handle higher speeds than pure HSS (but no where near as high as pure carbide).
Polished ones for aluminium, and suitably coated ones for steel.

Key thing is to ensure you are within the speeds/feeds specs for the drill, and as Chaz/Wal say, with Chinese spindles that can be a problem. You'll likely get better results on larger holes by either pre-drilling then milling to size, or just helix milling.

Spot drilling depends on what you're doing. I generally only use stub drills with split point (or whatever the manufacturer wants to call their self-centring drills), which I'll never spot drill first. However anything I need to use any longer a drill on, I'll generally spot first.