I run on the hills, often in temperatures down to -10 (I don't live in the UK), but sometimes in driving rain.
I wear a lightweight pertex when it's cold but I know it's not going to rain, sometimes with a thermal underneath - even in -10, it's all I need (and I'm a nesh southerner!
If there's a hint of rain, it's a thermal (or two) and a Lowe Alpine Triplepoint jacket (£80)- lighter than similar goretx jckets. Keeps me wrm and dry, but heavier thn option #1.
But as the weather warms up, you can't beat filet - I've got a £15 wndproof flouro one, which I bought in a bike shop.
So my v. unhelpful answer is ... you need all three so that you're prepred, whtever the weather!