Pro player here, been in pro rank for last 7 months (when I restarted playing gwent after years of inactivity, I reached pro rank in beta too). Monsters are good, they have a top 5 deck, but still no where near close to syndicate decks, especially iined pockets with bounty. Syndicate won't even let monsters reach sabbath in any of the 3 rounds. Absolutely destroys monsters.
Monsters go very even, point wise, with Spellatael, and edge out old popular meta decks like NR Foltest/stripes or seige, but lose to control heavy NG or SK. Monsters will beat most mill or thin type decks because they put out too much value if they reach sabbath.
I would say the best decks are not much different from last season, in the top 3:
1. Syndicate (Lined Pockets or Jackpot both OP, "The Scoundrel" is completely broken and is worth at least 13 provisions, not 10)
2. SK Reckless flurry Control (still easily beats monsters, lol, you'll be lucky to hit sabbath even one round)
3. Nilfguaard Ball decks with lots of poison/locks and Cahir
4/5. Spellatael or Relict Monsters. These decks both output similar amount of points over 3 rounds, consistently finishing within ~5 points of each other, the winner of these matchups rely heavily on tech cards to determine the winner.
Therefore, all the whining about monsters is just noob stuff. The truth is that both monsters and spellatael are the two best point generating decks this meta, and the decks that beat them also happen to beat just about every other deck (the top 3 decks). I think monsters get the most hate because they've been trash for so long, people are upset they have a viable deck again and streamers have been showing them off so they become popular and everyone faces them in games. But once you get past rank 3, you see tons of SY/SK/NG all day because those decks just kill anything you play and make tons of points in the process.
It's nice that Viy has been replaced with a monster deck that actually has interactive cards like self-eater.
Before nerfing monsters, there are other way more problematic decks that deserve a nerf first, especially Syndicate's unlimited tempo coin broken combos with bounty.