Three phase usually comes in around 7 hp and above. This three cyl compressor is running way under 5 hp. No capacitor because because this motor is worth 4X the other. Much higher quality.
If those welds check out good, and a test run went OK, I think I would lean toward the Speedaire because of the quality. Call a local motor shop and ask questions. The pumps are simple, nothing much to go wrong there. If you do purchase a used unit, as mentioned above, educate yourself on the parts and safety relief valves needed to function properly. Also, belt guards etc.
Vertical tanks are much more difficult to move around and work on. But take up less floor space. Most belt driven compressors that we would find in hobby shops and places like tire shops only run the pump at about 700 to 800 rpm. Most of the noise of this type is from the inlet port. They make inlet port muffler filters that make a big difference.
My 5HP Baldor motor turns at 1725 rpm and runs the pump at 784 rpm, draw 28.5 amps on 230 volts, pumping 23 cfm. This was a used pump when I purchased it in 1973.
Most really noisy small compressors will not be belt driven. And they will drive you crazy. A small pump on a large tank will run a long time when it kicks in. For most of our use, drilling and running a rivet gun and small dye grinders, a 2.5 or 3 hp belt driven single stage 125 psi shutoff on a 30 gallon tank will do it.
And make sure that the compressor is shut off when you are not with it. She will not like it starting up at 3 am..................
