Yep, get a synthetic insulation, it will stay warm when wet (or at least more so than down). My NorthFace one has a DWR coating, some don’t, but Flashy says TNF are chavvy so you’d best not get one of them 🙄 I think I get more use out of it than any other piece of clothing I own.
Personally I’d go to an outdoors shop and try some on. I found Rab and Montane versions didn’t fit me very well but I am a bit of a funny shape! Druidh is a big fan of his Montane one.
I haven’t tried it but the Colombia one with the foil lining looks like a good idea; I don’t know if it actually makes any difference to the warmth.
I’d also recommend getting a full zip so you don’t need to take your helmet off just to pull on your jacket for a few mins.