Buy this ring flash.
It packs enough wallop that I can take macro photos at 1:3 with 1000th second shutter speed. And obviously, it has TTL.
True, all us Canon users would like to buy the twin lite MT-24EX because it's the best flash for macro photography but it's around £800. For under £100, there's no better ring flash than the Dorr. And I've tried pretty much all the ring flashes out there, below the £90 mark of this one. They're not powerful enough. You could build a set up with brackets and an off the hot shoe flash unit with a diffuser. These work brilliantly and give you good modelling. But they require a lot of parts, building, fiddling and bodging and will set you back more money unless you're lucky.
I use this ring flash with a Canon 100mm macro as well as a reversed 28mm and extender tubes and apart from a bodge to make it fit on the reversed lens, it's blown me away. No more camera shake! The sharpness it brings to the 100mm especially, is remarkable. Out of interest, I took 2 identical shots of a dead wasp (it's winter in the uk!) one with the Meike ring flash and one with the Dorr. The Meike was ok, but the image broke down on the pixels zoom in. The Dorr showed every hair, every wing vein, every dimple up to the highest zoom in on my computer.
Don't waste your money on the bottom end £30 ring flashes. They're fine to start with, but you don't realise how much you have to work for every half decent shot where as now, I just have to worry about focusing. It's a relief.
Downsides.
Although you can adjust the intensity, you can't model.
It feels a little lightweight and plasticky.
Plus sides.
No LEDs so you get a realistic, warm result.
Power!
The price.
No excuse apart from lack of patience not to get great shots.