I'm not sure what your sales volume is, but if you are doing 500K (US Dollars) or higher, I would take a look at Cyrious. I've used their system in several companies and we will be bringing them in at the company I work for this summer. Its an extremely comprehensive system though. Its not just an estimating package. You can run the entire business from it. Take a look at it online and email Dean Sharp (dsharp@cyrious.com) and he'll be able to give you more information about it.
In my opinion its the best system out there, but I will tell you upfront that its expensive. The way I was able to justify the price to my boss was to look at it like this... If I can close more sales because I can quickly and accurately quote jobs, then I have more than paid for the software in the first year. Our close ratio for our customers is about 30%. If I can close 30-40% more of those sales then its a good investment.
You'll read reviews of the software online where some people hate it, and some love it. It really boils down to doing the work in the beginning when you set it up, to be able accurately quote jobs. No software can do everything. So many people expect to open the software box and immediately begin estimating. Its not that simple. Since there are many variables to estimate any job, those variables have to be setup. Then you have to determine if you are going to have the system price jobs by the square foot, linear foot, set price, or if you are going to use a cost-up model.
The mistake I see happen very often is that a sign shop owner doesn't take the time commitment that it takes to setup the software in the first place, and they are left with a useless piece of software that they paid several thousand dollars for. Its going to take alot of time to set up. Realize that upfront.
The other thing I see is that owners don't really trust the software to do the pricing for them since they have been doing it manually for so long. I was a regional director for one of the sign franchises here in the US and we would run reports for the owner to analyze the business. One of the most revealing things was that the percentage of price-overrides was many times 70-85%. A certain amount of overrides is normal, but I wouldn't want that to be more than 20% for my shop. A system that is setup correctly to begin with will save you time and make you money. Period.
Some of the other software out there is Activity, Estimate, Casper, CRC, Sign-Tracker and some other names. Everyone has their favorite. Do your homework going into this. Determine EXACTLY what you want the software to do, and how you want it to do it. Do a comparison of the top 3-4 companies you are looking at, and see what is going to work best for you based on what you want from the software and what they can offer.
Another tip... Don't take anyones word that a software package can do something. Make them show you. Write a list of questions and features you want to see and make them go through them all with you. What you will find is that you have to give up some features to gain others, or that there isn't a software out there that will do what you are wanting. But at least you'll know that going into the purchasing decision.
Sorry for the long winded speech, but its something I can speak with some authority on. Just my opinion. Hope it helps!