I don't have a lot of experience with either knife you're considering, although I have handled a Shield and was unimpressed. I think you might have a hard time converting any of these Hinderer design Kershaws to manual without drilling a detent hole and adding a detent ball. I know the Cryo has had mixed success being de-assisted. If you remove the torsion bar to make it manual, there's no force holding the blade in the handle when closed.
You could probably search this forum for more info.
If I had to pick a Hinderer Kershaw, I'd probably get a G10 Cryo.
Honestly, if you're looking for a good, manual bearing flipper that won't cost a bunch, your best bet would be some of the knives from Kizer Vanguard or RealSteel. If you can stretch the budget up to $100, you can get into one of the budget line WE knives which are excellent for the price.