Please oh please make it a high number. Like at least 100 medals. More would be even better. Make all medals count, not just the ones that currently count for the season objectives.
Don't make it based on matches played, and if you do, make it so that wins count for a lot more than losses. GSF has had enough trouble in recent history with people throwing matches for rewards (in particular there is a player who is known for logging into multiple accounts at once and queuing them all for GSF and then self-destructing on all of them), and I'd love to see season objectives that encourage players to actually try to win and fly well, rather than to just queue and throw for the rewards. I'm one of the top pilots in GSF, and I know for a fact that a lot of other top pilots feel the exact same way.
So my suggestion is to make ALL medals count toward a GSF season objective, that way players are awarded for assists and kills, which help progress the match. The previous (galactic) seasons objectives have either been based off of matches played - with little incentive to actually play well aside from getting 2x progress if your team wins - or been based off of only capture, defend, and damage medals. Capture and defense medals are only even available in domination matches, and to get them all that's required is to fly to a node at the start of the game and get the medal or capturing it, and then literally sitting afk under it for the defense medal. First of all, camping on a controlled objective isn't even usually a great way for good players to try to win the match, as attacking enemy nodes or moving between two controlled nodes for a more active defense is simply better, meaning that these medals only encourage newbies to go afk under a node for the entire match.
Instead of this, all medals should be counted, and there are lots of medals. There are medals for repairs, kills, assists, etc., which help your team to actually try to, y'know, win the match. Then just make the number required for the season objective be high enough that you need to actually fly in order to get it. Something like the PvP one where you have to get X number of matches with at least Y medals in each would be welcome too.
Before someone says something to the key of "omg she's an elitist and only wants the top players to be able to get it!" or something like that, no, that's not the case. What I want is for there to be objectives that encourage people to at least TRY. There are some who queue for GSF and not only don't help their team, but ACTIVELY HINDER their team and make them lose on purpose. PS please please fix the fact that self-destructing and respawning only to self-destruct again counts as "contributing" for the purposes of allowing a player to be vote-kicked.
Thank you for listening to my Ted Talk.