A skimmer is the very best at gas exchange, nothing comes close.
There is a small point that you have to remember, in very cold climates, where the house is shut up all the time, C02 levels can build up in the atmosphere, and so it will go into the tank, in this case, I recommend an outside air pump, or line to the skimmer.
A bubbler or two in a seahorse tank is good for the horses, they love to play in the bubble stream, and if you have a hitching post in the bubble stream, the horses will hitch there for ages getting all buffeted by the bubbles, a champagne bath.