For a knife that's meant for harder use, moderately expensive and up, my choice won't surprise anyone: axis lock. The axis lock is so much more reliable than a liner lock, it seems to me an easy choice over a liner lock. Add in the fact that it's likely much stronger, and ambidextrous, and there have been very very few reports of problems on the axis, and you seem to have a winner.
For this class of knife, these lock types are in my mind competitors of the axis:
integral lock (Sebenza style): the simplicity of this lock is definitely a winner. There are stories of these locks wearing very quickly, and I'm not just talking about the current story on the CRK forum. One reason that this lock format is so good, that white knuckling actually strengthens the lockup, appears to me to increase wear sometimes. But that's an awfully nebulus objection, and I think this lock format is very strong, and very close to the axis in terms of desireability. It's not ambidextrous, small objections.
Rolling lock: on paper just as good a format as the axis. In execution, the recent flamewar in the review forum has me a little wary. There were lots of reports of this lock failing, but on the other side, there's perhaps an economic motivation for these reports. Without taking sides, I'm witholding judgement a bit until I hard-use test one myself. Great format otherwise, though in execution so far it's not ambidextrous, again that's a small objection only for me.
SOG Arclock: Just don't know much about it.
Cold Steel Ultralock: Ditto the SOG.
For inexpensive knives, I feel the lockback works out well. It can be made to work well for more expensive knives as well, BUT it must be made carefully to avoid accidental release. For light-use knives, where accidental release isn't an issue, liner locks are a stronger contender, since their unparalled silky-smooth action is very nice.
Joe