Have you considered that 5E isnt the game for you, and you should possibly be trying different systems like GURPS, or Savage Worlds, or Rolemaster etc?
It just seems like you're set on intentionally playing 5E against several of the conventions that underpin the system, and its not working out for you as a consequence.
If you're unwilling to play 'with the grain' as it were, perhaps changing systems would be be better?
That way instead of trying to force a round peg into a square hole, you could be using a 'round hole' ruleset and be having a much better time of it.
There's a few reasons for this. We may eventually go back to Pathfinder. It's been discussed. Right now, no one wants to return to the complexity and problems of Pathfinder/3E. 3E has its own headaches. I had to heavily modify that game as well, just not quite as much out of the box monster modification as I've had to do in 5E. The monsters, specifically dragons and outsiders, had varied abilities that allowed for better tactics than close and melee or blast with breath weapon. Not sure why they went that direction with dragons and demons, but it is what it is.
The reasons people in my group are unhappy right now:
1. Myself. Weak monsters, badly designed modules with weak challenges. Too much work on my part to modify monsters to challenge my min/max players. But especially, the weak module design. I can't believe how badly designed these modules are. I used to love WotC modules. City of the Spider Queen. Temple of Elemental Evil. Against the Giants. Nearly every edition had good modules with some seriously dangerous challenges. These new modules seem so weak compared to past produced WotC material. Not sure what's going on with their challenge design, but it needs to be stepped up.
2. Player 1. Not enough options and splatbooks. He misses having new options for classes. We level and play through campaigns fairly fast. He likes to try new options. He feels like he's reached a point in 5E where there is nothing new. Every power seems the same to him with the advantage mechanic. Every strategy seems to be get advantage and attack.
I think the other two players are indifferent. They'll play whatever is played.