Just bought a pair of the 16801 crimpers. I've got a load of pins, but never had the right crimpers, so this will close out my tool gap.
For splices, spade lugs, butt splices, etc, I use an AMP T-Head ratcheting crimper. The non-return feature makes sure you put the right force into the connection, and you get a perfect crimp every time.
The only downside is you have to use AMP's PIDG terminals, which are expensive as all heck. These products are used in aviation and nuclear power.