Thinking about these two upgrades and thought I could get some input and give other new users like me some ideas into things they may not have thought about.

What were/are the best options for your machine and what made you choose that particular option?

32 bit and Trinamic stepper drivers seems to be the new hotness. Much much smoother and quieter operation from what I've seen so far.

Personally I'm looking at the Duet Wifi for my Rostock Max. The old Rambo is loud and 8 bit - and delta calcs could use the extra horsepower I think.

As far as LCDs go I use Octoprint or Astroprint so I'm not very concerned about that. All I want is a stop, pause, and start button :-)

Ender 3 (vintage late 2018)  I changed out the original controller & LCD to a MKS Gen L board and Reprap Discount Smart Display.   I went to the MKS Gen L primarily to get more feature memory with Marlin over the tight fit of the original controller & on-board connectivity for a BL-Touch. I could have updated to silent steppers at the time, but the noise isn't an issue so I used the same drivers as the original board (A4988).

The Reprap Discount Smart Display gave me a full size SD card slot instead of a micro SD.

The USB connection on the new board was not in an optimal location, so I got a short, right angled, panel mount USB type B extension cable & brought out the female panel mount to an easily accessible location.

There may be better options out there now, but at the time I did the swap it took care of my immediate wish list pretty cheap.

I've used the bigtreetech skr 1.3. Pretty easy to set up with marlin 2.0. And cheap.

I just installed the silent 1.1.5 board and it's been good.   Dramatic difference in the noise.

I would have looked at the skd board if I knew about it for a comparison

Duet maestro in an ender 3 and I have a skr 1.3 sitting new in the box I haven't touched.

I'm gonna switch to a duet wifi pretty soon for my ender and for all future builds.

Bigtreetech has some very nice drop in 32bit boards for the ender, and their tft35 v3 is pretty sweet.

How happy you are with it is going to come down to how good you are at configuring firmware.
Its not terribly difficult, but the is a pretty steep learning curve there.

just ordered the SKR mini E3 and a BL touch so once I get them I will let everyone know how the install goes. I had some reservations about the mini e3 not quite being up to snuff in their firmware when dealing with probes but it seems like the solution has been found and just needs to be forked in on github so we will see.

so what's the benefit of the SKR over the Creality board?

@Iguana775 Mainly a boot loader to update firmware but with a board like the mini e3 they also provide dedicated ports for stuff like a bed leveling probe or a touch screen instead of having to use a break out board or cutting and splicing into the ribbon cable. The other side of that coin though is you have to feel comfortable enough to configure it in the firmware then flash it to the printer

Cool.   Maybe I'll do that one day.   I'm pretty happy with my 115 board right now

As far as LCD's go I am a big fan of Repetier on a PI (just upgraded mine to a pi4)
Repetier server

Just put a Creality 1.1.5 board in my Ender 3. Just for the 2208 drivers.

I think pretty much any board on the planet is an upgrade over the ender board

In the case of the skr, waayy more powerful cpu (32 bit), and some extra pins for whatever random gizmos you want to add.
There are quite a few different skr boards out there with different chips, pins, etc. Iirc, 2 of them are ender specific to fit the goofy form factor. Im sure people have drawn up adapters to put the more standard sized ones in.

What about running something like Octoprint?    Does it take any changes to an Ender 3 Pro to make it work?

I use a raspberry pi loaded with octo pi. Doesn't really require any changes to the Ender 3. The only minor issue is when its hooked up to the octo pi with USB it tries to draw power from usb which is just enough to work the screen and give you some pretty good coil whine at the hot end. The redneck ways to fix it are either electrical tape on the proper pin of the USB cable or just cutting the cable open and cutting the power wire. I'm sure there is some more elequent software solution to stop power over usb but I haven't really researched

Honestly unless something goes wrong with your main board rock it till something fails or until you want to build another printer.  I replaced my OEM board on my Tevo Tarantula because one of the stepper drivers burned out and they're soldered direct to the board.  Went with a MKS Gen 1.4 and am happy with it.  Still cheaped out on the drivers and got the ones with a purple board (DVR something or other....its' been a few years).  Did nothing for the noise but increased resolution some.  Was too cheap to spring for the silent drivers for another $20.  The noise doesn't bother me, but that's because I don't stay in the room with my printer.

If you do need a board get a Gen L V1.0 or go big on a Duet board.  Having onboard WiFi is kind of nice, though I have so many Raspberry Pi's that are laying around configuring Astroprint is, well was a year ago, a breeze.  My hypercube is going to probably get a Gen L board and the same drivers or maybe the silent drivers.  TBD on that project, have about 10million other things ahead of it in the queue.

LCD's I get the cheapest display possible.  DGAF about touch screens, color, or big screens.  The budget display tells me everything I need to know, at the moment at least.  If I go with a multi extruder setup when I rebuild my Tarantula I very well may change my opinion on the budget screen in favor of the larger, but still budget, screen.

If running the rpi, can run Klipper firmware. Im not positive because the ender runs a tiny chip, but should.
Klipper basically has the rpi as the brains of the operation, and then forwards commands to the ender board.

Its basically a bumpstock for 8bit boards
They claim as good as 32bit, but still not 32bit.

My Ender 3 Pro is sitting in pieces on the desk I'm going to run it on.  I need to get it together so I can see how well it works.    It's been a long week....

Yea,  I think you can use the stock board with klipper and a Pi.  Look up Teaching Tech on YouTube