BK Precision 1550
This is a switching supply.
The up-down adjustments would make this a non-starter for me.
CSI3005X5
A whole bunch of companies re-brand this unit. They're actually fairly decent. The voltage pot is a 10 turn, the current limit is button-driven in 0.03A increments.
The most common resaler of the power-supply is MPJA. It also comes in a bunch of voltage and current ranges: 0-30V 5A, 0-60V 3A, 0-120V 1A.
One thing you can't see in the pictures is that the unit has a set of screw terminals in parallel with the output banana jacks, below the cover plate labeled "EXT OUTPUT". If you need more permanent connections, you can use the screw terminals.
The schematic for the whole supply is available. This makes it enormously more repairable (and hackable) then ANY of the others.
BK Precision 1671A
The funky extra output connections on this make me nervous (speaker terminals? really?).
I would guess that the potentiometers are single-turn, both from the artwork on the case near the knobs, and the fact that it does not mention multi-turn knobs, as that's normally a significant selling point at this price range.
On the whole, If I had to choose from the supplies listed, I would wholeheartedly recommend the CSI3005X5, more because the alternatives are considerably worse.
Anyways, I would say that even if you don't think you need a floating output power supply (what you really mean when you discuss a separate earth terminal), you almost certainly will find it useful in the future, so I think you shouldn't dismiss it. Just being able to string multiple power supplies in series for higher output voltages is tremendously useful.
It is very likely that there will be no problem connecting them in parallel, as long as you can get the Voltages close to equal. A few mV will probably not matter. It is unlikely that current will flow into the output of the lower voltage supply unless it is the type of supply specifically designed to operate in this fashion (e.g, Hameg).
You could try asking the manufacturer about your question, although if it is "fake" then that might not matter. Also, you could consider renting a beefy supply just for this project.
Not all supplies can be put in series. It depends on whether they are isolated from Earth ground. Yours probably can be put in series, because it has green jacks (for "Earth" ground.)
Good luck to you.
Best Answer
So this question is actually about electrical device isolation and earthing in case of fault.
It doesn't afford any protection in the case of a bare PCB. Connecting PCB GND to earth doesn't stop you touching the hot terminal on your IEC input connector if you have one. Some guys build nixie clocks that run off 200V generated by pumping a 12V supply. All rules and safety precautions are thrown out of the window when you have the raw PCB exposed. "No user serviceable parts inside" comes to mind. European CE marking will save you from being totally vaporised if the encased circuit behaves as designed, and in a limited number of fault situations.
I often use two Korad three terminal 30V supplies in series, and there's no way I can think of to zap myself other than sticking 60V into my mouth. That wakes you up. As soon as you introduce another problematic device to your circuit, anything might happen.
The main point of earthing is to enclose the whole device in shield of metal. If a wire comes loose then it shorts against the earthed case, resulting in either the internal /external fuse blowing, or the earth leakage circuit breaker triggering. Simply connecting the PCB GND to earth is more of a noise reduction strategy. I asked about the merits of metal enclosures in Are plastic enclosures safe for hobby mains voltage projects?.