I'm not a wise one on the breadth of gear, but those regs are what people mean by good basic ones from a main brand, diagram are nice for less salt in the works, the SP Mk2 piston first stage might serve you as well, as SP's cheapest but rock solid. .
If you check SP's published specs, the Mk2 is their lowest performing reg, by far. And, since it's an unbalanced piston - their only unbalanced 1st stage reg, I think, I wouldn't really recommend it to anyone as their one-and-only 1st stage reg. I would use it as a reg on a deco bottle. I'm not sure I'd want to be using a Mk 2 on a single tank dive, if I happened to be at 130' and a near-panicked, out of gas diver came up to me and wanted my octo. Maybe the Mk2 would flow enough to satisfy two divers at that depth, with at least one of them really huffing away. But, I would rather spend a little extra to avoid having to find out.