I made lots of mods, both 'tried and tested' designs by others and bespoke parts designed by me. It improved all my various printers (I didn't previously mention that I once ran a print farm of monoprice mp10 and mp10 mini's too), but one day I realised my time was worth more than doing all the upgrades and mods myself, so I took a chance on Prusa for sheer reliability right out the box and never looked back. Building the mk3 was a joy, with excellent instructions in full English. All the parts supplied were top quality (Trinamic driver stepper motors and beautifully made parts with no poorly finished sharp edges etc.). I'd really enjoyed learning and tinkering with my earlier printers, but I'd come to the end of that road and welcomed the ease of ownership the prusa seemed to bring. Since then I've updated it to the mk3s and added a raspberry pi with camera and octoprint. It all just works. Print quality is excellent and, contrary to some people's findings, the auto bed levelling is exceptional. I certainly don't miss having to adjust the bed screws after a print was hard to get off the bed. And that literally never happens because the prusa uses instantly removable spring steel sheets with various finishes suitable for the different filament types.It all comes down to what you want as a user. I'm glad I learned about the relative basics of 3d printing on cheaper, more 'hands-on' machines, as I learned loads. But I love the sheer productivity, reliability and ease of use the prusa affords.Re. CoreXY, there's loads of info online to read about the potential highs and lows of ownership. Prusa are just about to release the XL, a CoreXY machine that looks very promising. lol. Good luck, whatever you choose.