After too many electrical issues we've gone to always using the proper crimping tool for each connector. It's been a considerable expense, but when your tool lists the pull-out strength for the wire and has a UL listing you can have confidence that at least your wiring won't let you down. The ratcheting design, by design, eliminates (most) operator error by not opening until the crimp is finished.
A well done crimp doesn't need solder, and solder may hurt both its electrical performance and durability (it becomes brittle).
For the generic terminal crimps we use Thomas & Betts Stakon connectors with the company crimping tool. I've tossed everything else out. We also use tools from Anderson for the Powerpoles (battery connector and 15-45A) and have been using Tyco Series 1 connectors and their excellent tool. This year we're also trying the Hansen Hobbies tool for pwm connectors, but may go pro for that too. Good tools are a pleasure to use, do a better job, and last a lifetime.
Here's a great overview of crimping and how to do it well:
http://www.molex.com/pdm_docs/ats/TM-638000029.pdf