There are two basic types of lasers: a CO2 laser and a Fiber/YAG laser. While Fiber/YAG lasers are primarily used in the industrial marking arena, the majority of lasers used in the signage & recognition markets are CO2 lasers.
Which manufacturer? This question will take a bit of research to find your best fit. You will want to know the current models, how much power you need, whether or not installation support is needed, set up, training and/or technical support is offered, and whether or not the machine is scalable in the event, you want to add a stronger tube in the future. This is definitely a time when you want to measure value vs. price.