We had an all in one waterproof one - at 12 months she wanted to crawl around in the outside so just fleece really didn't work because she got sodden
At 18 months she now wants to toddle around outside so again waterproof seemed best (plus wellies !)
We have the all in one fleece for keeping warm but otherwise just bundle her up in jumpers and add the waterproof on (Jojos do one that packs into its own pocket which we keep in the buggy)