I do know that you have an hard crush on Wijnaldum and that you also hated Can and now apparently not convinced with Fabinho. I am thinking you hate physicality in the midfield.
I am the exact opposite of you. I thibk Wijnaldum is no where near close at Fabinho at breaking counter attack and winning ball in the air. I believe playing Wijnaldum as holding midfielder would be a great mistake, he is very passive in his defensive game and not agressive enough not to mention he is at best when he can dribble and control the play with short passes.
Fabinho is the closest thing we've had since Mascherano. He has long legs and great timing and he is great at breaking plays with his tackles. Something we have been lacking for so long. Henderson, Wijnaldum are very passive defender and hardly ever make slide tackle. Milner and Fabinho are way more agressive and wins way more ball.
Fabinho tackles are a thing of beauty. Even backchecking he is able to make perfect tackles which is very hard to do while not getting a red.
I'm not speaking from a place of 'what if' though, I'm talking about facts. Nobody was dribbled past more (usually led to by a missed tackle) in Liverpool's midfield (per game) than Fabinho last season so hardly a perfect tackler, and Wijnaldum was one of the top 3 midfielders
in Europe in that respect last season (IIRC). He has played the 6 already a decent amount for Liverpool and the statistics back up that when he is our 6 is when we have our best defensive numbers. It's not just that I really like Wijnaldum; it's also backed up by the results. Slide tackles are super risky which is why, IMO, most of the best defenders/defensive midfielders only use them if absolutely necessary (how often do you see van Dijk go to ground?) As far as the aerial part is concerned...it's not really an issue, when you read the game well the only place you desperately need to win headers usually is close to the box and our defenders are more than capable there.
Can was awful and our team was always better without him, and improved by leaps and bounds after he left (him refusing to stay despite Klopp wanting to keep him was such a blessing for this team).
I'm fine with physicality if it's necessary, but it's usually not. I don't have anything against Fabinho (he's a massive upgrade on Can for example), but at the end of the day I think the 6 might not really be the best place for him and I'm not sold that he can be labeled as 'world class'.