Both systems have their flaws.
The old Spawn system was very predictable and often spawned you extremely far from the objective, really making you feel like you're getting handicapped by the random nature of the system. While the new Spawn system gives you multiple spawns to chose from, many areas have very one-sided spawns which means that one team spawns west and the other on the east side of the objective. (Same with North and south side, duh) While the new spawning system made spawns much less predictable it also introduced Car Spawners which in my opinion are just something you can't balance properly while keeping it viable. Car spawners along with a few other things have also changed the Car Meta as there are very few Vehicles who can actively cause the enemy team to 'waste' resources to take out said Car spawn. Not to mention that the whole Grid-based system behind Car spawners is fundamentally flawed.
I personally don't mind the current Spawn system as it was a step up from what we had many years ago, it fixed issues but brought its own. I think that working on the current spawning system and making improvements to it can have a huge impact on how the game flows and overall player enjoyment. The main points to look at are shifting spawns, when spawns should be pushed out and therefore further away from the objective, some areas that have very few viable spawns to take and therefore leave you with very predictable ones, spawns after being teamkilled and then Car spawners itself.