Some variation in sound between devices is not unusual, as there could be slight differences in the alignment of the drives in their bays which could cause more or less vibration, which might sound like a faint hum as the drive starts up. It's also normal to hear a soft rattling or clattering noise when the drive is working hard, such as during bootup. Disk fragmentation can increase this noise significantly, but that is unlikely in a new machine.
If you are hearing basically the same noises from all the machines, and the difference is just in how loud they are, that may just be a difference in the quality of the mounting, or a loose connection, not necessarily a serious problem. Nevertheless, if the noise is loud enough to be disruptive, you'll want to contact the manufacturer.
A recurring occasional ticking sound is a bad sign. That suggests that the drive is defective, and may fail soon. If I had a brand new machine with a drive making that sound I would backup any important files immediately and initiate a warranty replacement.
If noise in general is a concern, you might want to consider getting SSDs instead of HDDs. Noise, power consumption, and reliability will all be better with SSDs, and prices have come down significantly recently.