The Ender 3 pro was my first 3D printer; so, I hardly knew anything about how the machines worked; the lack of clear instructions was somewhat tricky. Luckily, Youtube has many videos showing how to assemble it and the critical adjustments needed to ensure a successful build process.
On the other hand, Prusa has a beautiful, well-documented build process broken down into digestible sections, making the build process easy and fun. It does, however, need a few critical updates. For example, the bearings need to greasing during the installation process, which they say not to do. I ended up having to take the whole machine apart the next day to grease them properly.
The Ender and the Prusa are in different price brackets, so it isn't easy to compare their build quality. Both machines have their strengths. Creality builds the Ender to achieve its print quality at the lowest price possible. It does this job well using cheap commodity parts that are easy to replace and cheap to purchase. I appreciated this in the initial days when I would have a hot end meltdown; being able to run to my local MicroCenter and buy replacement parts for $5 was a huge relief especially late in the afternoon when I wanted to start an overnight print.
Prusa, however, cut some corners where I would have preferred they hadn't, especially at the price point. Look, I've seen the videos of the print farm at the Prusa factory, how they use it to perform quality assurance on parts to improve the design. It makes perfect sense to me from a technical perspective, and I'm sure the parts meet all of their manufacturing criteria. I still can't help but wish Prusa would produce 5% of the critical components using metal or another more robust material. They often use square nuts in a plastic housing, which can easily strip, making it hard to secure critical parts like motors and pulleys. Being plastic, you can reprint a new piece, but if this your first or only machine, that could be a pain.
Calibration is key to good print quality. You can find many calibration models on the internet and across forums to help fine-tune your machine, all of which work just fine on either printer. When it comes to software calibration, I think Prusa takes the lead. The dual rod design and nine-point support on the build plate help create a solid build surface that is practically worry-free. Once you add in the first layer calibration and the machine's first-time start-up wizard, you are 90% done. Sure, you can do an extra bed leveling test to fine-tune it, but for your average printer, this will due. The one exception to this process is disabling Crash detection. Crash detection caused every single print to fail that in which it was enabled. Prusa needs to do something about this feature. I was shocked with how poor it performed (in my experience*) You can see in the pictures how on clean models it would randomly cause layer shift. Before you say anything, no, it was not caused by loose belts or grub screws.
When it comes to calibrating the Ender, as long as you follow the tips found in Youtube videos on leveling the frame and bed, you should be pretty good. That is to say initially. The method they use to level the bed with springs, only using one Y-axis support for the bed frequently, has me struggling to get the bed leveled. Once leveled, it will work well for a while before eventually needing a retune. Sure, there are many ways to address this, from BLtouch's to EZABL sensors, even plugins on Octoprint to help account for leveling, but the machine's job at the end of the day is to print quality objects. I feel it wouldn't have added much cost to an Ender to add a second-bed support rail which would significantly close that calibration gap between the two machines.
There isn't much to say here. The print quality between the two is very close. When tuned well, the Ender will give you 99% of the print quality of the Prusa; if you are willing to do the work, the savings are significant! If all you want to do is set it and forget it. The Prusa is definitely worth the extra money.
Maintenace is a wash between the two machines. They both have their strengths. Rails on the Ender are basic and easy to disassemble to replace parts, while on the Prusa, the bed rails and x-axis rails are time-consuming and challenging if you need to replace a bearing. Wiring when replacing a hot end on the Prusa is way more accessible with the electronics mounted on the side. With the Ender, you have to flip the machine on its side, potentially causing your printer to need recalibration. Don't get me started on belt tensioning. How Prusa has come this far with their belt tension system is beyond me. It is cumbersome, difficult to tighten, hard to replace. Just all-around terrible. They could solve much of it with the same type of tensioning screws Creality uses on their machines. I think both need to take a page out of each other's playbook. It would certainly make it much harder to justify the Prusa price premium.
In the end, both machines will print quality pieces. It comes down to two factors. How much time you want to spend working on your printer, and how much you want to pay. Luckily for us, you can't go wrong with either choice.