If we're talking everyday ideal defence then i vote the humble walking stick.Incongruous and non threatening while still being a highly effective tool,both straight and crooked canes are extremely versatile weapons.
For shtf then in the UK the 12 gauge shotgun to me rules supreme,i would take a gun over anything else and the 12 gauge is one of the most effective weapons if kept under 50 yards for shot.Use improvised ball or slug and you can double that range,(not that i would ever advocate researching on how to make such a load)
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Also it is by far the most common ammunition in the UK.
If guns are a no no then a spear would be my first choice,either ready bought or improvised.I like bows and shoot them but as much as a ranged weapon is preferable neither the bow or crossbow is on the top of my list.The crossbow is slow to reload and the bow requires constant practice,and i'm not sure i could trust either in a high stress situation. A shotgun or polearm would be my choice,unless concealed carry is a concern.
It's all a trade off.For concealed carry a good quality telescopic asp ranks high for me (though illegal to carry).If the rule of law and order no longer applies i'll be concealing a british service kukri.