We are always asked which is the better printer between thermal and impact. If you don't already know the differance Thermal Printers use heat sensitive paper and the printer creates the image with heat, impact printers are the old standard using bond paper and an ink ribbon or roller with the print being made by striking the ribbon against the paper with a series of small dot heads.
If I was choosing a register or POS printer I would take a thermal printer most every time. There are still applications where an impact printer is useful, for example a kitchen printer where two color print is needed. But for speed, ease of use, and duribilty a thermal printer can not be beaten.
The cost differance is not much between printers, but the offer all cost of ownership is much lower in a thermal printer. Thermal printer do not have the failure rate impact printers have, and the paper is much easier to change.
Oh but you might think thermal paper is to costly right? We yes you are going to have sticker schock the first time you but a case but there are a few things to remember about the price. The first being you do not have to buy ink ribbons, also there is almost always more feet per roll in a thermal roll compared to bond paper.
Hope that helps!