Digital pianos are increasing in popularity. Technology has improved, and piano sounds are getting more and more realistic. Best of all, all digital pianos can be volume controlled and be used with headphones. There are many manufacturers today, so what are the differences between the different manufacturers?
Generally the heavier it is, the better it is. A grand piano has the heaviest keys. The better digital piano keys are made of wood with more "sensor points" to simulate more realistic piano touch.
In layman terms, the piano sounds, how 'good' the piano sounds although this can be very subjective to individual. Most digital pianos have 3 levels of sampling. Some of the very high end models have up to 5 levels of sampling like the Yamaha CLP480. Advanced pianos use physical modeling instead of sampling technology, like the new Viscount H series.
Recording tracks, drum rhythms, editing, different sounds, polyphony, USB, MIDI, SD slot, etc, self learning capabilities, editable parameters, effects, etc
A powerful amp with larger speakers will sound much better even at low volumes. But if you are always using headphones for monitoring, the amplifier and speakers serve no purpose.
Portability, polished material, piano cover, slim design, etc.
As you can imagine, each digital piano scores well in certain aspects only. For example, the Yamaha CVP 601 has many functions but loses on its keyboard touch as compared to Yamaha CLP 575. The CASIO PX860 has stunning slim design and build but loses on its functions. The Yamaha CVP 609 has every aspect but you pay a price for it. Thus, it boils down to your budget, and what you really want from a Digital Piano. It doesn't quite matter even if you are a beginner because an expensive Digital Piano still benefits.
If you are unsure because you are a beginner, you should go without it. However if you like to have your Digital Piano to be versatile and be able to do many things, you can consider the CASIO CDP 230. If you are able to pay the high side, (above $2.8k) you should consider the Yamaha CVP 701 or Roland models. Do consider that all Digital Pianos should have other basic sounds like Electronic Piano, Strings, Organ, etc. And most Digital pianos have a built-in metronome and even a simple 1or2 track recording function. If you require to connect your Digital Piano to a computer, look for models with a USB port. Technically all Digital Pianos can be connected via MIDI port, but a MIDI to USB interface cable can be expensive (about $100) compared to a $10 USB cable.
If so, consider the CASIO CDP 135 or YAMAHA P45. The CDP 135 is the cheapest, and has better keyboard action as compared to P125 in our opinion. Yamaha digital pianos generally produces mellow tones whereas CASIO sounds are brighter. All of these models are below $1k.
If so, consider the CASIO PX series, Roland F series or the YAMAHA P series. Do take note that every Digital Piano is portable in a way. The piano can be detached from the stand easily. However the bigger cabinet pianos like the Yamaha CLP and CVP series will be more troublesome to disassemble. Another thing to note, all 88 keys digital pianos are about the same length (dimensions). It is very much the depth of the piano that you should be concerned about if space is a constraint for you.
If so, consider the Yamaha YDP or CLP series. It has a very nice cover, and the prices are affordable. Nice piano sounds and weighted action. You can also consider the CASIO PX870 or AP series.
Most important of all, you have to like the Digital Piano. Even if you like it because of its looks, it is still a valid factor. Bear in mind you will technically pay a little more for Yamaha for the brand. Casio is always well known for value, and unlike in the past, CASIO has moved on, no longer just a calculator manufacturer. Roland and Kawai are slightly more expensive, especially in Singapore (For some reasons) but they are good makes. KORG is surprisingly cheaper in Singapore than in other countries. If money is not a problem, consider the latest Viscount series (made in Italy).
We cannot recommend just one particular model for you, we will usually work around with your budget first. If you are looking for the cheapest, the CASIO CDP 135 is it. If you are able to pay nothing more than $1.5k, you can consider the Yamaha P115, or CASIO PX 160. If you are willing to pay above the $1.5k mark, you should consider a Yamaha Clavinova if space is not an issue for you. The entry level Clavinova will be the CLP525, which we are using it for all of our piano studios. The CASIO new PX 870, Kawai ES8 and Yamaha P255 are good portable digital pianos.