Best Archer out of these options?

Depends on the team. Summer Arturia is my obvious general choice of the three.
If you need a farmer, go with Atalante.

If your Squirtle is only NP1, stick with Kuro.

Atalante is quick servant, so the team building is a bit different since her role fits more for farming with an Anti-Army 10 hit count NP.

Generally Archuria > Kuro > Atalanta. But situation could be various.

Archuria > Kuro since basically SSR > SR, and depending on NP level. Archuria is more deadly for challenge bosses, but Kuro are more relying on support. I can say Kuro is top SR and deserve to be grailed to lv90, but you only have NP2 and want to make comparison with Archuria. So that is. Also if your Archuria is NP2 then Archuria wins totally. Why? Since NP2 Archuria can make her 2ns skill more useful.

Atalanta... Well, So far she is good for farming, but 2 major drawbacks make her hard to use in NA: (1) poor NP gain, maybe the worst level, even though you got her 3rd skill maxed, still her Art card is in poor performance. So normally you should build a team for her for better performance, like build Quick team, or 2030 Waver, or Critical team for better NP gain and Quick Niche. (2) Building team for her but so far lacking of decent Quick support. Skadi is amazing but Skadi is only available 19 months later for US. Others like Waver and Hans are still not the most ideal support (compared with Tamamo to Kuro/Archuria). Meanwhile, her skill lasting is short which means she is shinning only when high-level skills is a kind of precondition.
Atalanta is never the poor-performance Archer. It just need patient to get her high-skilled and building a decent team around her. But she is only good for AOE farming if you give materials for Archuria and Kuro as first priority and won't invest much for Atalanta.

Only use atalante with a kaleidescope or equivalent. Mlb 3 star ce giving 50% is fine too.