Delta has one of the more restrictive basic economy products, and "Economy Light" on Air France and KLM is not as restrictive.

If you book an AF*-marketed or KL*-marketed Economy Light fare, you will...

1. Earn SkyMiles, MQMs, and MQDs, according to a multiplier of distance flown based on the fare class (see this page on delta.com for the tables).
2. Be able to choose your seat for free (on a DL-operated flight) or for a cost / free with elite status (on an AF, KL, and VS-operated flights).

Note that airfrance.com and klm.com sometimes book you on DL-marketed flights, so it's not guaranteed that you will get the AF* or KL*-marketed flights.

VS*-marketed Economy Light fares have their own fare class (T), which still earns SkyMiles but Delta recognizes as Basic Economy on their flights so you do not get advance seat selection.

I've flown on a lot of KL*-marketed basic economy fares, if you have more specific questions please ask.