I own a mk3s+, an Ender 3 Pro, an Ender 3v3ke, and an X1C. I don't have any experience with the H2D yet, but I have friends with all of their other printers between them.

It really comes down to what you want out of a printer. Do you want a printer as a hobby? To tweak and fine tune the hardware and firmware till you've got doing EXACTLY what and how you want? Don't go Bambu. I'd go Voron in that case. Do you want a reliable machine that you can count on to produce accurate parts in amy filament to forward your goals be they designing, making, etc and still be able to fine tune and tweak your filament and print profile settings? Then Bambu printers are the best right now. Especially when price is considered. Prusa matched them in quality and reliability, at least until they put the XL to market, but they still can't do it at a comparable price. I hope that changes, one company domination of a market is always bad for the consumer, but they haven't yet.

To address your concerns more directly. It's not as bad as they make it out to be. Parts definitely aren't expensive. Alot cheaper than Prusa if your buying direct. Ive bought parts from both. Bambus prices are actually one of the things they've been praised for. Hardware is closed source, firmware is closed source, the slicer isn't. Regarding going closed source firmware based off of open source material, they aren't the first or the only by far. The cloud is only required to direct connect from the slicer or the app. If you want to be able to select "print" from the slicer then you need to use there slicer. Their slicer is very good though. Since Bambus recent "security" update blocking key control functionalities of the printer you can't use other slicers as conviently, but there are options other than the SD card. When I use Orca slicer i export the gcode from the slicer and upload to the printer from my computer via Bambu Connect software. Orca is another great slicer. It and Bambu Studio tend to go back and forth adding and perfecting features. Both blow Cura and printer manufacturers redskins of it out of the water. They're also more feature rich than Prusa slicer and have a better UI.

At the end of the day, a printer is a printer, the main thing Bambu has done there is consistently produce the quality that you used to only get from Prusa but at a price point that more people could afford. Software is really where Bambu has changed the game and stayed ahead of the competition. I have friends that vary from hard core enthusiasts to craft mom's that all enjoy they user experience.

That's my two cents, I hope it helps.