Who's better Kuro or Squirtle(Archer Artoria)?

Can i add an extra question? who is better NP1 Archuria or NP5 Kuro?

Probably Squirtle but only because she's a 5 star and has 5 star stat weights. Both of them np spam but both of them do it in very different ways. Both of them have ways to avoid big boss damage, one through an evade and the other through a near continuous charge drain. That charge drain though and the attack and crit gen (for males) up give Squirtle better team viability than Kuro though.

For the future, appmedia has Squirtle as the 10th best servant in current JP among 5 stars (she's the 4th best Archer on the list tied with Orion and behind Tesla and Gil) while Kuro is only top 20 for 4 stars. The fact that Squirtle remains a top tier archer and 5 star even 2 years after her release is relevant while Kuro has slipped just a little (not a lot actually. Just a lot of servants got buffed and I believe farm is given a weight while Kuro's niche is boss killing) to 18th(3rd best Archer behind Tristan and Atlante).

Both are doing different things. Chloe is a selfish ST NP Archer, while Squirtle is doing things from team. She increases party's defense and attack for 3 turns, which is really nice. Also her Arts buff lasts for 3 turns, while Chloe's buff only for one turn.
At NP2 Squirtle with 10/10/10 is just straight broken, she can NP loop for like 4 turns. And the heal on her second ability is really good, shame it drains 10% of your NP gauge.

Archer Artoria