I prefer EC. It's scientifically correct. ppm is a sort-of measure as the ratio between ppm and EC is not a constant, but dependent on the types of ions in solution.

I also actually prefer single purpose meters. They are cheaper to replace parts etc.

There is a new meter called 'Trident' that measures nutrient temperature, ec/cf and pH...

In the real world, there is no such thing as a PPM meter.
PPM is a mathmatical calculation.
Only EC can be measured. Some manufactures of meters made a wild guess as to what the PPM might be for any given EC.

Norm

Thank you for the recommendations.

Norm hit it on the head.

PPM has to be measured in a lab, and each specific mineral has to be tested for and measured independently. Just the name "PPM" says as much. "Parts Per Million" - of what?

It's like asking somewhat what they brought for lunch and they say "food". Sure, but what kind and how much? PPM is just a unit of measure, but you have to designate specifically what you're measuring or it's just a vague concept.

I like that lunch analogy.

Well to give credit where it's due, I borrowed that from my son-in-law. He's a consummate smart-ass and that's one of his regular "jokes". Not everyone really enjoys his sense of humor, but our family has always been a bit odd.