Favorite Slicer opinions?

So with my new printer being imminently ready, I'm starting to look at setting up a profile for it.

To date, all of my printers have run Marlin, and I've always used Slic3r to generate gcode to run it. At some point I installed Cura (No idea what version) and it seems to want to be the default application for .STL files, but I've never even tried to configure it for my printers. Chances are that I installed it 5 years ago when I built my I3, and ended up getting Slic3r working (As I recall never particularly fine-tuned to it.)

Whichever it is, I'll want to be able to switch between 2 different printer profiles. One will be running Marlin, the other RepRap Firmware. The printers have different bed configurations and build heights, so they will need to be kept separate. It would be a "nice to have" to make switching between profiles simple.

I'm probably not willing to spend money on slicing software, unless it has some pretty amazing features.

Overall, I'm not unhappy with Slic3r, though sometimes it's picks for what order to do the infill in or the orientation to do a bridge in make me scratch my head.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

I use Marlin for my printers, I have gotten used to hacking and using it.
My two slicer/printer programs are CURA (Free) and Simplify3D ($150).
There are things that CURA does great, that S3D, not so much (dealing with oddball meshes).
There are things that S3D does great, that CURA, not so much (dual head prints, supports).
I have never used repetier, nor slic3r, so I have no opinions there. (I did have Repetier on one of my I3's once, I liked its menus better than Marlin, but I replaced it so I could upgrade to multi-head hotends.)

DLC

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Kits: Folgertech Kossel 2020 upgraded E3Dv6, Anet A8 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head, TronXY X5SA Pro(E3DHemera).
Scratch: Large bed Cartesian, exchangeable heads, Linear slide Delta, Maker-Beam XL Micro Delta, 220x220CoreXY.

I have experience with few. Sli3er, Sli3er(PE), Cura.

and...

I always ended at raw Sli3er. Its fast, intuitive, easy, there is everything what user need.
Cura is slow. I do not like interface, it is difficult to use. Tried it many times and always went
back to Sli3er. And Sli3er(PE), it is tuned for Prusa printer so I do not use it also, after
I tried it, went back to raw Sli3er.

If I need any slicer it would be Simplify3D, but that price make me stay away.
What I have seen it offers best slicing options.

KISSlicer, in my testing and print quality comparisons beats every other slicer.

I've tried KissSlicer, S3D, Slic3r and Cura.

I keep going back to Cura. The latest versions (3.4 series) have stepped things up in terms of overall quality of prints for me. Including excellent support generation. I've had the opposite experience from Arnold. I prefer the Cura interface and had terrible experiences with Slic3r being slow and interface being rather dated and clunky.

question:

is it possible in KissSlicer to make changing parameters through layers, I mean speed, retraction, temperatures ?

For example:

1-10 layer - retraction 5mm
11-20 layer - retraction 6mm

...

Well, for the time being, I've set up another printer profile in Slic3r.

It seems to work pretty well, and I got my first successful print in PETg ever. Still lots to tweak and fix.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts