Some notes:

Auto bed leveling is completely overrated. On a decently calibrated printer on a decently flat surface with decent spring tension you need to level the bed maybe once every few months. Auto bed level can also only correct small misalignments and it does so by skewing the one surface of the print. It’s at best a small gadget to make the first layer overly perfect, and it’s totally not necessary.

Powerloss recovery can be enabled on every printer by using (or compiling) the firmware with that setting enabled or by using an external print server like octoprint or repetier server. But: if enabled in firmware (not on an external print server) it causes bad print artifacts and wears down the SD card rather quickly. I have had a single time in 6 years of printing where I accidentally turned off the power mid-print and not a single time where I had powerloss due to things outside of my own stupidity. It’s not a feature that I’d place any value on, unless you live somewhere where power outages are very frequent. Also, if you recover after a power loss and the hotend has cooled, it needs to be heated up in-place to basically melt the hotend free from the print. You will have a massive gash at that point.

Filament runout sensor is a nice gimmick, but again only important in special cases, namely you intend to print really huge parts that take multiple rolls to finish. Otherwise you’ll just use the last bit of filament to print small things.

Size: I’d recommend you a bed that’s 220x220 to 240x240 as this is the standard size. This means, you will be able to print almost anything you find online without issues. Larger only matters if you have specific use cases in mind. Prints that huge will take very long to print though (longer than a week), so you might not want print anything larger than a standard board anyway.

Without enclosure you can easily print PLA, PETG, TPU/TPE and filaments based on these materials. You need an enclosure if you want to print ABS or Nylon or other specialized materials. An enclosure helps to keep the air warmer and draft-less to avoid warping for filaments that tend to warp. Also it allows you to use air filtration to avoid the toxic fumes that ABS or Nylon tend to create during printing.

Surfaces are a solved problem by now. They will all work fine. The only difference is cosmetic. I personally would go with a textured surface since all the other sides of a 3D print are slightly rough and it looks a little dumb if one side is super smooth.

One thing to really watch out for: Before your first print (and if your prints stop sticking) wipe it thoroughly with a cloth rag soaked in isopropyl alcohol (IPA). This is a step that you really shouldn’t skip, otherwise your prints won’t stick to the surface.

Used printers are a massive gamble. There are many things that can be subtilely broken or damaged that you will not notice if you don’t know exactly what you are looking for. It will just print really badly and you’ll never figure out why without the propper knowledge. If you don’t want to tinker a lot, don’t get a used printer.

Both the Mini+ and the Ender 3v2 Neo are really good printers. The Ender 3v2 Neo will get you a bit more for your money, but the Mini+ is really cute and comes with free Haribo.

Speed is not important? Are you sure? Is this your first printer? I though that too at first, but trust me, you are most likely going to want speed more and more once you get going. Also, 3D printing is pretty much synonymous with tinkering unless you have some sort of business model in mind, but if you do… (see comments about speed).

My take, go with lightly used mk3. Market is primed for two reasons - first, in US at least there is just less of a sellers market lately for anything used and with recent Mk4 release people are looking to sell to upgrade.

Wish you luck with whatever you end up with and have fun and don’t be afraid to tinker!