You can't compare them at all, it's like saying Kog'Maw is the ADC you should lock in whenever possible because he's 'more valuable' than the other ADCs.
And supports don't take CS. I don't think you're getting the point of a support marksman at all, Kindred and Ashe have utility regardless of their scaling so which make them good picks for specific match ups and lane partners. That allows them to pick up black cleaver with tank items or whatever the team needs.
If they can cover the ADCs weakness (lack of sustain, peel, or even damage), that makes them a good support, things like gold reliability are a bonus, and are only required if it directly affects their ability to work well with an ADC (let's say Janna had 0% on her slows and scaled with a lot of AP, that would bar her from working with early game slow reliant ADCs very well)
Kindred has sustain and zoning along with HP tank shredding that puts her in good terms with ADCs that shred armour tanks, and require space to position well, or require a buildup in damage.
Ashe has her W slow, E vision control, passive slow, and ultimate stun. Make her a tank and she can't be ignored by champs that don't have a huge dash or blink.
Lulu has a lot of defensive buffs for fighting back and soaking damage, Zilean has level transferring, semi reliable AoE stuns with a slow or movement speed buff to a single target, but that doesn't mean they're the only choices.