Major upgrades options? (Hotend/extruder/sensor combo)

Ottobawt

Goals/TLDR:
I want the best experience, while remaining mainstream and "practical" on the budget. (Corvette vs Ferrari) Components that are well known/supported, "affordable".
I may avoid Unjustified-Proprietary parts.
I try to focus on significant upgrades first. Game-Changers.

My ignorant thoughts:
If going on intuition, because of the quantity vs. quality of information.
-Start with the hotend and sensors, then upgrade the rest based on that.
-Go down the Rapido or Revo path, and try to supplement with universal/cheaper components when practical.
-Get the Accelerometer and Flow sensor.
Current Setup:
-Four Duet2 printers. Delta printers(D300VS).
-E3D Titan Aero(Direct Drive), Copper volcano/nozzles...
(non-CHT, eager to try...clones?).
-FSR Pads for calibration. Reprap firmware.
-Average achievable flow rate: 20mm^3/mms.
-XY speed 70mm/s with 200mm/s travels, before artifacting becomes too ugly.
-Majority is PETG/PLA, 0.8 nozzle, may go up or down a size as needed. (I like to print with fine shell layers with chunky infill,)

?Question Section?:

Hotends and Nozzles:
I think the popular systems are the Revo, Rapido, Mosquito, and Dragon?
Some of which are more propitiatory than others... but there is adapters that can make things work ether way?

What hotend/nozzle style combo is a sweet place to be?
Are there downsides highflow options when available?
Revo + V6 CHT adapter maybe? (is that possible?)

Extruders:
The couple that I've heard the most about are the Orbiter, and the Hemera XS.
This may be my last step in upgrades, as it's probably the most costly/time consuming, I'll have to design/print new delta specific parts... but I may have to do that for other add-ons... so... it may be in for a penny in for a pound.

Will a modern extruder show meaningful results over my "trusty" Titan-Areo?
Is there motor/extruder tech, that works with the Duet2 on a soft/firmware level?

Sensors: (last but not least?)
These are these easiest to understand on paper, but I wonder how significant they are in practice?

The Accelerometer helps counter the effects of speed artifacts. How much does it help? Is it more/less effective on a heavy setup?(my Direct Drive Delta)
Flow sensors/Filament Monitor; Can it adjust flow rate to maintain accuracy?
Better heat probes/temp sensors. I had one that came with a used printer, but it was hyper sensitive/problematic and removed it... but now that I'm wiser, I wonder if having accurate static heat is more important than I once thought, could I get some feedback?
How obsolete are my Delta FSR pads? I've felt like these have been a great calibration system; but if there is room for meaningful improvement? I print on hair-sprayed, textured-clear glass, onto of aluminum.
Any thing else that I should consider upgrading/advancing to get higher quality printing?
Is the duet2 a limiting factor to what meaningful "sensors/add-ons, available?
-any future tech on the horizon to factor around?

Thank you for your time in reading this, and for any future recommendations and thoughts!