Either can give a reliable connection if done correctly or either can cause problems if done incorrectly. If I'm using factory type terminals I crimp using a quality crimping tool. When splicing I use a but splice as described by Chevl_Steve, except I use double thick shrink with sealant (available from Hi-Line) This
pic shows the crimp tool and the crimp you end up with. The tool along with a Varity of jaws or mandrels, will cost about $100.00. Poor quality crimps are asking for trouble as well as improper soldering techniques. Any one watch the American Hotrod "Junkyard Dawg" when making the positive battery cable the starter end terminal was clamped in a vice, heated with a torch and filled with solder. The cold battery cable was then installed in the terminal, can you say cold solder joint. Guarantee there will be problems with that solder connection in the future, More often than not too much heat and too much solder is used, the solder runs or wicks 1/4" or more up the wire. When the wire is moved it can easily break where the wire meets the terminal.
Use which ever you prefer just do it right and end up with a trouble free connection. Personally I prefer crimp.
I have also personally installed "Pile connectors" multi pin connectors designed for aircraft, the gold plated pins or contacts, as they call them, are crimped on the wire using tools designed specifically for the Pile connector.