I have been doing missions and I always seem to end up with the Soldier medal at the end.
What criteria do I need to satisfy to earn different medals? The only other one I have seen is Artillery.
According to the EA website:
The playstyle medal you get at the End of Expedition (EoE) shows you which Legionnaire’s Feats you scored highest on for that Expedition. Once your XP and playstyle medal are awarded, your Feats reset to zero so you’re ready for your next Expedition.
Feats
Feats are small challenges, in five categories, each with bronze, silver, and gold levels.
When you’re out in the world, track your Feats in the Journal section of the Cortex.
Most of the Feat categories are inspired by Legion of Dawn Legionnaires:
Source: https://answers.ea.com/t5/General-Discussion/What-does-the-play-style-medals-mean/td-p/7496266
Players have also found a General Tarsis medal, which appears to be from doing all the Feats at gold level.