I could only afford a 14 and settled to novels on it quite happily. I'd get an ache in my finger from scrolling so often rather than reading.

I'm happy with my 20 when on road: it fits neatly on ny lap or over my shoulder on a strap. were it lighter I'd be happy using it more on my feet, but as is is it works best whilst sitting or having a surface to work on.

For coding at my desk, a 40 is ideal. Also the buttons on my Focus are amazingly useful when it comes to various computer games or other esoteric tasks. For code review and proofing I also find the space of the 40 useful, although anything wider than my computer keyboard would irritate me I think.

So the answer depends on you I guess, hopefully my experiences might be some guide.

For coding and general use, 32 is my minimum. I have a 20-cell Orbit, and while it works, it's not great for me. I found an old BrailleNote MPower on Ebay last year for $65, and grabbed two of them. One is broken, but the display looks in good shape. The other works beautifully, but has no battery life. It lives on my desk, connected to the PC vaia serial and to power from the wall. I love it. If it ever dies, I can try swapping the display from the other unit I have.

Mine was a case of incredible luck, though. Displays off Ebay are a roll of the dice--was it cared for? Do the buttons work? Are there dead or stuck dots the seller doesn't know to look for? Don't hesitate to try Ebay, but be careful and know the return policy.

In general, I'd go for 32 or 40 if you can. Also consider whether you want a braille or QWERTY keyboard, ,if wireless connectivity is important, which scrolling you prefer, and--the big one--if there are cursor keys. I dislike the Orbit 20 mostly because the placement of the scrolling keys is awkward, and there's no cursor routing. If I'm reviewing code or editing text, I'm not going to scroll ten lines down, find a mistake, then have to arrow down to it. I want to hit a button and have my cursor in the right place right away. Remember that the Orbit 20 lacks this feature, but the 40-cell model has it. It's not cheap, but it's less expensive than any other 40-cell display bought new. If you can get used to the scrolling keys, and don't mind the loud and slightly slow refreshing, it could be an option. Orbits really are loud, though, so keep that in mind if you'll be using this in classes or other quiet places.

Most people can do with 40.

Depends on personal preference. I'm a teacher for students with visual impairments and I find that my younger kids do well with lower cell counts but my older kids need lines of 20 - 40. 14 is really small, especially if you're going to be using it so heavily. I'd probably recommend trying a 20 or 40 cell device before purchasing a mini device. Also, You can find refurbished displays at decent prices.

For example here's a 40 cell display for about $1500.00 USD
https://irie-at.com/product/hims-edge40-refurbished/

Here's a 20 cell pacmate display and qwerty keyboard combo thats refurbished and under $300.00 USD.
https://www.ebay.com/itm/PacMate-Omni-QX420-Windows-computer-4-blind-20-cell-Braille-Display-Refurbished-/252415937624

Here's another pacmate braille display qwerty combo with 40 cells for $350 USD
https://www.ebay.com/itm/PacMate-Omni-QX440-Windows-Laptop-4-blind-w-40-cell-Braille-Display-Refurbished/251737587926?hash=item3a9cbac0d6:g:75YAAOSwuMFUejZk

Personally, I've never worked with the braille display/qwerty keyboard combos but they make a lot of sense to me for adult and professional users.

This one is a bit excessive but here's an 80 cell braille display for just over $700 USD after shipping.
https://www.ebay.com/itm/Freedom-Scientific-Focus-80-Braille-Display-Keyboard-F80/293589884387?hash=item445b521de3:g:nHsAAOSw7pNeyS~5

I honestly wouldn't bother with anything less than 40 cells. My main use display is 80 cell and it's really handy, especially for technical content. Bear in mind that code gets indented. 3 blocks at 4 spaces each are already 12 characters, so you get... 2 more characters on a 14 cell. That's useless, and means you'll be scrolling all the time.

I use the orbit reader which is 20 and the braille me which is also 20 and I like it. It’s small and readable and fits comfortably in my lap and I sit and relax and read

Hi there-

selling one here used from the UK if you're interested?

https://www.ebay.co.uk/itm/293940838595

it's 70 cell.

I would definitely try to take into account how the different displays scroll. I am very happy with a 20-cell display, but I got one without thumb-keys and I really hate it because I get problems in my fingers and wrists from either (a) having to raise my fingers from the display to press a scroll button, or (b) needing to use two hands while reading to get the scrolling done. I agree with the other person who commented about code requiring a larger display probably, but just in terms of regular reading, I went through over a thousand books with an 18-cell display. But if the scrolling isn't comfortable, then the smaller the display, the faster things will get uncomfy. Of course not everyone will have my experience. However, I just want to prevent anyone from having the same problem I did. I used to read a ton of books, and now I hardly read braille just because I despise the scrolling method on the display that I got. I hope you find the perfect display for you! I'm looking into purchasing the Chameleon or Mantis display next, personally. The Chameleon is 20 cells and the Mantis 40. They both have thumb-keys which I find to be the most comfortable for when you know you'll be on the display a lot.