I send my spouse postcards with drawings, notes, and photos on them. A photo makes the job much easier and quicker. I use the Instax Wide after spending a few years with the Polaroid Mio back when it first came out (and I had to get it imported from Japan). I find Instax prints too small, and the Instax printers quite a bit blurry.
I have tried most of Polaroid's portable Zink printers and camera/printer combos and I found only one that I like. The cameras are really terrible, worse than my phone and the inability to easily (at least with the models I tried) get an image from a phone to the camera and get it to print was either impossible or too cumbersome to be of much use.
That said I love my Polaroid Zip printer even with it's numerous faults. It has poor battery life. The programming cards included with the film sometimes cause the printer to exclude usable Zink paper. (I prefer the Prynt paper with adhesive. It makes adding it to a postcard all the more easy. I just use the programming card for the standard paper.) The battery life is not stellar. It's more than a year old and I get about 3 prints per charge if I do them one after another, but I have an external battery pack that I cary already- problem solved. The software lacks function, has a poor UI, and does not accurately show color as the printer would print it. The software is fantastic at updating the printer's firmware.
I don't like the standard Instax size, but it holds up well (I have prints from a decade ago) and is perfect for adding to commonplace books or postcards, but the aspect ratio seems odd to me. Weird as I like the Polaroid Zip paper, and it's smaller in size.
My suggestions: get the lomo from Amazon, get a few extra packs of film, and if it doesn't work for you return it, and you are only out the packs of film. Stay away from the Pogo printer or the camera printer combos.