Digital pianos are like any other technology – always improving with time. However as a classically trained pianist, I can say that nothing beats the real thing. What a digital piano can’t replicate is the mechanics of an actual piano. Behind each key is a complex mechanism consisting of levers, hammers, dampeners and other parts which give each piano a unique feel. When rapidly pressing the same key, one can hear the differences in tone between each press as the mechanism is physically moving so that the hammer can hit the strings. You can feel it happening through the keys. The soft pedal, for example, on a grand piano actually shifts the action so that each hammer only strikes two out of the three strings for each note, changing the sound and tone. This obviously can’t be replicated authentically on even the best digital pianos.
My advice to anyone wanting the best digital piano for their budget is to do what I did: buy the best quality, second hand, real piano you can afford. In my case it was a Yamaha upright. Don’t buy a brand new piano that looks nice but has an inferior touch and sound to an older, higher quality piano. That being said, if the budget is extremely tight, at least buy a weighted keyboard that boasts a realistic touch over sound quality. The last thing you want is to one day sit down at a real piano and discover you’ve been learning practically a whole different instrument.
Good luck and happy learning.