"I've tried working with cheap LED's & bulbs off eBay, like strips, 3W beads and 30-100W big modules. They have poor quality light - shadows, blue/yellow fringing, small spots of light, gross colour temp (blueish), run hot etc. Just too much hassle so for now I settled on a screw in bulb."
The COB LEDs are significantly better in terms of giving a uniform wide field of light, with good colour and no fringing. Flicker is also a problem with some readymade LED bulbs if they run from unfiltered rectified AC. Unfortunately the only way to find out is to buy and try.
As mentioned you can get readymade constant current SMPS, and they seem to have a relatively ripple-free output compared to the tiny regulators in readmade LED bulbs.
Flicker is a concern for anyone doing close work because it can give you headaches even if you don't notice it.
I have a converted halogen desk lamp for PCB inspection work. This originally used a 12v 20w capsule fed from an ironcore transformer, and while it was a good light source, heat was a problem for close work. I gutted out the head and fitted a video card hs/fan with a 10w COB. In the base I added a bridge, decent size filter cap and one of those cheap Chinese buck units, the type with current limiting. A pot on the base, replacing the ten-turn which was on the buck unit, provides brightness control. Now cool running, and brighter than the halogen on max setting.