Those torque-key type wrenches are great. I only have one, the original Ritchey version which is 5nm. I use it a lot for stems mostly, but it does my seat post collars fine too
For other stuff, I have two simple beam type torque wrenches
an old (discontinued) 1/4 inch drive Park that goes to about 7nm. Works for almost everything other than cranks and cassettes.
a craftsman that goes to about 70 or so nm, so it's perfect for cranks, cassettes, the heavy stuff.
Click type are easier to use, but more expensive and I tend to not trust them mostly because I started with a cheap one and it wasn't accurate. I'd wager the normal priced ones (i.e. good quality) are fine.