You really need to set a budget for this purchase since you can get a very nice laminator, for example, in the $5000 range or you can go to the next level for $15,000. It depends on your intended use and volume. I suspect you are in the $5000 range (I wouldn't recommend anything lower than that and I definately would not recommend any Chinese import or the Daige), so let me offer the:
Royal Sovereign RSC1400H (Possible older model #, I have not researched the newest model #s)
5 roll holders - paper • media • laminate • liner take-up • media take-up
Heat Assist
Cost effective
Excellent performance
Excellent reliability
Excellent support, warranty, service
Actualy, I own this particular laminator and I never use the heat assist for general sign purposes, so depending on your specific needs, you might be able to elimininate the heat assist for some cost savings but the 5 roll holders are of critical importance.
If you want to go to the next level, I would suggest the Seal Pro Series. For the extra $10,000 you get the brand name, supposedly easier roll holders to swap material out with, generally percived greater value, and possibly higher volume processing.
The last thing I'd like to say at this moment is that purchasing a laminator is not like purchasing anything else. A laminator may last you many, many years. It is a simple piece of mechanical equipment that will outlast digital printers, etc. Therefore, you should anticipate your future when purchasing a laminator and purchase one that will be size appropriate for you future needs.