More and more I prefer to have both options available. I usually paddle a sit on top and have wet legs at all times. For water below 50, I use dry pants over 1 mm wetsuit pants that are the newer really snug and stretchy stuff that I wear over wicking tights like underarmour. For water temps below 60 I remove the dry pants. For water below 70 I remove the wet suit pants and put the dry pants back on. For water above seventy five I just wear the tights or shorts.
On the top:
When it is freezing I wear a wicking shirt, a fleace shirt, and a dry top. When it is really cold I wear a dry top over a wet suit 1mm shirt over a wicking shirt. If it is not too cold wear a wicking shirt and a dry top. And if it is mild I wear a wicking shirt and a splash top.
If I know it is going to be rough and I am going to be swimming a lot like for a day playing in the surf my dress changes completely. I wear a wicking base, followed by a 1mm neoprene base followed by a 3mm snug neoprene waders. ( Neoprene waders should be snug like a wet suit) With a slpash top over it all. Must often I end up quickly taking off the splash top as the bgginess of it gets in the way of swimming and I get to hot. But I put it back on along with a cag as soon as I land to rest so I don't cool down too fast. Most often I am landing to catch my breath or just to cool down and have a snack or a drink. Dressing for a day of really rough stuff for me is very different for dressing for a trip.