I’ve got a Stages one sat here waiting to be forwarded to a friend. It seems to be the most adaptable, cheapest and best for those wanting to swap between bikes – it is only a LH crank arm that weighs 20g more. Simple and well made – just needs a UK distributor.
And a weatherproof innertube boot to cover it 😉 . I wrote off two in bad weather earlier this year. So for the third, I cut a 15cm section of brompton inner tube and slid it over the crank, then sealed both ends with electrical tape. I am happy to say that it has survived the ultimate rain test of a severe rainstorm on the A10, whilst mounted on my roofrack at 60mph through France on Friday night.
Mine is Ultegra and you’d never notice the cover was there. I added one of their free stickers to try an bling it up a little. I’ll take a phot if anyone is interested.