I've been using the Skratch Labs everyday hydration mix.
I like that it has no funky ingredients and a good balance of electrolytes. Flavor is very mild, certainly not bitter or metallic.
It kind of has more citric acid than I like during my long runs. It's fine on my stomach for before/after.
That it comes in bulk has plusses and minuses. It's good that it doesn't waste packaging, and that it can be mixed into a hydration bladder without having to release pressure as you would for an effervescent tablet. But then, it's harder to carry on the bike or in my travel carry-on, and because it doesn't have anti-caking agents, you have to be careful to store it COMPLETELY airtight (100% metal, glass or ceramic container with a good seal on the lid, no plastic lids).
I haven't tried Osmo.