I've had pro-settler folks say it was in fact Dayan's decision to ensure there was not a refugee flight away from the West Bank that was such a problem though IMO I'm uncertain whether that would be so helpful; could Israel politically relinguish enough land in 1967 for a peace deal--I'm uncertain. I agree in terms of most secure Israel the best way is probably to hold the West Bank in 1949. Another interesting possibility is an earlier rapprochement with Jordan (it was a long time coming) in say the 1950s (low probability I think). An interesting POD is Jordan not attacking in 1967. I'm not sure what the result would be (for Israel to be viable it needs resource sharing agreements with both Jordan and Syria so the water in the Golan, Kinneret, Jordan Valley and the West Bank are all available) but it could't hurt--the settlement enterprise is enormously problematic for all kinds of reasons.
The best case scenario (plausibility-wise) is basically an Arafat* who accepts a workable Camp David Agreement. All the other scenarios, save perhaps Jordan not attacking in '67, seems very unlikely. Indeed the Israel controls the whole mandate scenario is highly unlikely because the Arab Legion was actually skilled. That being said a different 1948, particularly a unlikely victory at Latrun and Israel holding on to the Old City at the end of the war would be helpful for Israeli security. Another, more intriguing possibility (assuming the goal is Israel and not a binational state), is a different post-WWI arrangement whereby some sort of Arab state is formed rather then mandates, and an accompanying Jewish state is formed alongside the Arab state. This would help make Israel's security being dependent on the Arab state, rather then the rather more complex scenario in place today.
Alas none of these are terribly high probability (indeed IMO a binational state is unworkable for all kinds of reasons, and was likely to degenerate into a similar situation to what we have today).