Can anyone recommend a really good boot for my Rottie bitch's front paw.  She has bilateral ED, one side is worse than the other.  She is on daily painkillers and seems pain free and is very active but she has worn down her nails on her favoured side and we are getting very close to them getting sore.  So many boots available I don't know where to start.  They need to be protective, waterproof and to stay on. Cost not an issue just want a really good boot (pref a pair so I always have a clean one)
Thanks

Ruffwear boots are popular amongst our clients. These in particular: http://www.ruffwear.co.uk/dog-gear/dog-boots/grip-trex-pairs (You can find them cheaper elsewhere). But I don’t know that they’re waterproof, possibly could be used with Pawz rubber dog boots underneath? Is there a reason you want them to be waterproof?

I assumed if they got wet through and heavy with water they would be more likely to come off.

One of my dogs has (long story short ) "problem paws" and always wears Pawz boots in wet weather.  They stay on, are waterproof rubber (but eventually nails will wear small perforations so if you must have 100% waterproof you'd need to check after each wearing), come in packs of 12 - cost is variable online but I expect to pay between £10 and £16 per pack.  Most importantly, the dog is happy to wear them: they are lightweight, and made of strong rubber so they don't soak up water and he can still feel the ground under his paws.  Without knowing the level of protection you need, they may or may not meet your requirements.

Had this with our elderly BH, scrapped/dragged his left foot as he walked, a couple of nails worn right down (bleeding) & occasionally the top of toes. Couldn't get on with a boot as the extra clearance required to lift his foot just tripped him up.
Tried everything I could think of, in the end just had to manage his walks on a daily basis, road walking reduced & increasing soft surfaces, if his toes got so bad  I'd built the nails up with super glue!

I think you may struggle with finding fully waterproof ones tbh.  I used to use Neopaws on my old boy for his arthritis and joint troubles, and they did help him - not cheap but worth it.  They have molded soles and neoprene uppers so help keep the foot warm when it's damp, and the soles are waterproof.