What is a single word adjective that means "particularly useful"?

For a given task, like digging a hole, many things are "useful". The set of all "useful" things contains, among other things "spoon", "pencil", "saucepan lid", "shovel", etc. There is a subset of this first list that contains "particularly useful" things like "shovel", "hoe", etc. Is there a single word adjective for "particularly useful".

Examples of how the word "x" might be used

"For the purpose of our investigation, these data points are x"
- A note on this one: This is actually very close to the sentence that brought me to post this question. I don't want to convey that the other data points are not useful. Neither do I want to convey that without these data points, I can't get the job done.
"A shovel would be x for digging that hole"

PS, I am not looking for "vital", "critical", "indispensable", "invaluable", because those all are stronger than what I'm looking for (they mean "so useful that one can't do without it", not what I'm looking for).

Solution 1:

apt, most apt, most relevant, perfect, ideal

also: best

Examples:

"A shovel would be most apt / perfect / best for digging that hole."

"For the purpose of our investigation, these data points are ideal / most relevant."

These are all common words so I will leave the reader to check the definitions if needed.

But note, this question is borderline off topic.

Solution 2:

For the purpose of our investigation, these data points are valuable.

A shovel would be valuable for digging that hole.

If you can't do without something, it is invaluable. If you lose a valuable source or item, however, you may still be able to complete your task.

valuable (adj.)

Of great use or service

valuable advice m-w

If you describe something or someone as valuable, you mean that they are very useful and helpful.

Many of our teachers also have valuable academic links with Heidelberg University. Collins

Of great use or value to a person or for a purpose. OED

This changed the interpretation of data; ethically the research took the changes made and as a researcher there was a feeling that some valuable data was lost. However, according to Tappan (2001) validity and truth of claims from this perspective was established through agreement, rather than empirical tests:... Maina WaGíokò; Transfer of Education Leadership Training Skills (2016)

Solution 3:

Advantageous works in some cases:

Your Dictionary

Advantageous

The adjective advantageous is useful for talking about things that are beneficial, or helpful, like when you find an advantageous spot to hang your yard sale sign — a spot where all the passing cars can see it.

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