Archer currently performs very well against many matchups due to recent changes. Supporting Minis like Lumberjack gets an indirect buff since they pair well with the Archer.
AA
Since Archer is currently used a lot, Minis that are useful to go against them becomes a common pick as well.
Miner is a reliable way to get to the enemy backline. Its upgrade also makes it easier to take out enemies because of increased damage.
Fisherman can be a gamble but is a strong option to counter many Minis, especially if your opponent likes to use ranged units that are placed on the backline.
Prince works great as an anti-frontline unit, but is also a good way to reach the enemy team or their backline pretty quickly.
Spear Goblin's clash is strong since it can potentially take out an enemy unit at the start of the round, and is slightly less risky than fisherman since you can at least hit a frontline unit if you want to be safe.
A
Most frontline units aren't used that much in the current meta since they can be ignored by Archer, but they are still good for many decks, especially if you play a ranged hero like Royal Champion.
Giant Skeleton is still a reliable frontline unit to soak up some damage and deal damage in an area before going down.
Ice Wizard is a good option against speed-based decks to slow them down, but won't be that effective if your opponent focuses on their backline as their main damage dealer.
Skeleton Guard can be a pretty cheap and efficient tank. Using the Soul Jar special tile, Skeleton Guard is guaranteed to use its super.
B
Some Minis are too costly to use, while some are lacking synergy with good decks.
Royal Ghost often doesn't survive long enough due to its low HP to effectively use its super. It's also 3 Elixir, so not as efficient as some of the other Minis.
Dart Goblin is still a powerful ranged damage dealer, but it doesn't deal with tanks fast enough, and having low HP makes it go down quickly from enemy Archer.