As far as a soft tail bag, I have an Ogio tail bag, and I looked at Cortechs, which are nice as well. They don't come with locks, but I am in the process of finding a lock for the zippers, and a wire/cable lock to tether it to the bike. It's economical as the bags are pretty expensive as is everything related to bikes. After buying your bike, paying insurance, getting your helmet and gear, upgraded parts, gear bags, and GoPros, etc, the total cost of ownership add up! I guess, it's not most elegant solution, but if I am riding, the locks should be enough deterrent and I won't be keeping that much valuable stuff in it anyway if I am away from my bike. I use it for my phone, wallet, extra keys, phone,etc while I am riding, which I will take away with me when I leave my bike. Plus, the Xena nd Kryptonite locks for my bike which I store in my tail bag, I'll be usuing to lock my bike probably.
If you want to look at a hard shell case with a lock, and locking mount to the bike, a lot of people swear by Givi. They are really nice and functional, though I have no personal experience with them. I looked at them for my tank and tail bag before I settled on the Ogios, which I love. Givi are pricey, but you seem to get what you pay for regrading them. They have bike specific locking mounts depending on area.
Hopefully a Givi owner will chime in. You have a lot of research to do @matt323. When I start comparison shopping, I spend hours looking at features and doing pro's/con's lists.