building my first 3d printer

Hi, i live in Europe, i'm a university student and i've read articles about 3d printer since 2013, but i've never built one due to cost, time, etc. Now i was thinking about building one and finally print something after 2 years reading forum and 3d printer comparison..
I have already had all the eletronics at home except the nema 17 and i'm pretty good in soldering and this other stuff...i was interesting in the P3 Steel and CoreXY, because it's my first printer so i can understand better how they works and they are relatively cheaper than other one.
I have a budget of 250-300 € (eletronics excluded cause i've already have it), and i want, if it is possible, to reach a good quality printing...
Do you think is better a p3steel or a coreXY in term of print quality, stability and learning?

After reading some post i've choosen a smartrap core...