I've always used Marineland Maxi-Jets. They are my favorite pumps and seem to be perfectly matched to the Remora I already have. I bought this skimmer about 10 years ago (unfortunately I paid full price), and I've only had to replace the pump once. The current one has been running 24/7 for about 4 years. Power outages and even running dry for a while don't seem to affect it at all.
The Cobalt looks almost identical to the Maxi-Jet so they might have the same manufacturer. The Cobalt costs about $10 more, so maybe it is better/quieter, although my Maxi-Jet never makes any discernible noise unless it touches the glass. If the Cobalt is truly an improvement over the Maxi-Jet, it must be one awesome pump.