Q:

Which dot matrix printer is recommend for ubuntu (10.04 or +)? 

I need to buy a better dot-matrix printer and I am currently using the Epson LX-300 (like IBM pro printer)
I found in resellers:

Epson LX-300 II, FX-890, FX-2190, LQ-2090 OKI ML1120, ML320, ML620,
  ML621

A:

Ubuntu Wiki lists Epson Printers that have been tested on the currently supported version of Ubuntu. 
As you are not fixed on one model you can browse through these by clicking on this link
Make sure your printer is compatible
More help is available here at the Linux Foundation where you can enter the name and model of the Printer and it will tell you if its compatible
I did a little bit of research and fear your options maybe be limited, you may also find this link useful

