• the Gripen would be a great choice for a more air-defense-leaning QRF/frontline fighter, as that last bit was an explicit design goal of the airframe
• the Rafale would be a great choice for a more multirole-oriented fighter, as its heavier, has (iirc) longer legs, is twin-engined, and can can hold more ordinance (both in terms of mass and hardpoints)

I’m sure Antonov and the Ukrainian government in general would be happy with either, but if they have the opportunity to get both and learn from both (in terms of construction as well as doctrine and deployment), I’m sure they would jump at the chance.