I know it’s probably not as simple as this, but : Which is warmer…? I’m cold intolerant. 
Drysuit/pants/jacket will definitely keep you warmer. You can dive in Arctic waters with a proper drysuit. Wetsuits work well but water does get in. However, once water gets in it doesn’t circulate much, and warms up which creates a layer of insulation. Wetsuit with a splash jacket works well for me. The major practical consideration is how much you want to spend.
I was hoping the packrafting suits would be out in time to make this a moot issue, but alas… it isn’t going to happen. 