I got a Prusa (MK2s) six years ago and it's been really, really great. Unfortunately, your budget restriction rules out the current model.

If you can get access to a printer at a friend's house, a library, a school, a workplace, a makerspace, etc., I would suggest not buying a printer while totally new to 3D printing. Do some 3D printing for awhile. Then, on the basis of that experience, decide if you want to commit to having a good printer at a slightly higher price point.

400€ is really very restrictive. Commercial 3D printers are 10,000€ to 100,000€. Prusa's printers are extremely good for their modest ~900€ price.

If you do decide to get a Prusa, I recommend the kit over the assembled option. It's cheaper, and the familiarity you get with its components and construction during assembly gives you the power of fearless repair and tinkering -- you've already assembled it once, so disassembling it and reassembling it for repair or upgrade is no big deal.