It would be good to have a pair of both. Breathable for Summer, Neoprene for Winter, so long as you don't have to walk far in the Neoprenes! Simplest option is to go for breathables, but with good, warm, fleece kex/leggings under them when it's cold.
On the subject of warmth, and with the colder months just round the corner, here's a great bargain! Micro fleece lined Winter trousers from my favourite outdoor clothing company!
Craghoppers Kiwi Stretch Winter Lined Trousers -Regular length | Craghoppers World Travel and Walking Clothing
£55 down to £16.50.......they were only £15 last week!