Here are the more common types of Accordions:
The Piano accordion type is widely popular in the US. This type of accordions features keyboard like keys for the right hand, whereas the buttons on the left hand play the role to provide the bass accompaniment.
These type of accordions features keys for the left hand and for the right hand too. On a diatonic accordion, for a single key, the pitch of a specific note varies as the bellows are pushed or pulled respectively. A diatonic accordion uses only notes from some scale.
This type of accordions have more popularity in Europe compared to the US. This type of accordion features buttons for the right hand (treble side) and the left hand (bass side) both. Varying from diatonic accordions, chromatic accordions come with all the sharps and flats, also with all the naturals.
Where all the other types of accordions come with straps that are worn around the shoulders of the accordion player, this type of concertina accordions have to be held and played with both hands. The concertina features buttons for both the right and left hands.
The Right Fit
Considering the Fit is the first thing you should check for. If you wish to gain full control of your accordion, then it shall be assured that it properly fits your stature. With the right fit, the accordion is locked in a position accordingly with your shoulder straps and is placed in a way which places 60% of the weight on your lap and 40% on the shoulders while sitting down to play. We know having a large accordion can feel to be very overwhelming.
But if the accordion is too small it can prove to be just as difficult to play. If the accordion is too short, the accordion will not be able to rest on your lap; which will, in turn, put 100% of the weight on the shoulders and will make it feel heavier. This also allows for too much movement and constantly adjusting the position of the accordion again and again
The Right Size
Accordion players usually have to make a choice between the portability feature and variety of notes. 48 and 72 basses are the best options for people who are into folk music, but you can get the full range of notes, and range of sound from the registers on a max size 120 bass only.
With 120 bass and 41 treble keys the piano accordion is the max sized model, the bass side provides a chromatic scale and all the chords, which are arranged in 6 columns of 20 buttons. The six columns are counter bass notes, root notes, major chords, minor chords, 7th chords, diminished chords. An 80 bass features 5 columns of 16 (omitting the diminished row), and a 37 treble note keyboard. Whereas a 72 bass has a 34 treble note keyboard but has the 6 columns bass.