I don't have a recommendation on a particular system, since they are all made by the same 1 or 2 companies, and everyone just puts their label on them.
The $99 specials they show on TV are a good way to start, but they usually only include a cheap model controller, 2 contacts for the door and perhaps a motion detector. You will need more than that. Contacts for all windows/doors on the 1st floor and basement (including windows and bulkhead if applicable). A motion detector or two for the large rooms, expecially rooms that provide access to other areas of the house. My house has one main room which all other rooms and halls feed off, so motion detector in that room effectively protects the entire house.
Although you may have contacts on all the windows/doors, a second or backup level is served by the motion detector. Although the system and all contacts should be tested regularly, no one ever does it, so if you have a bad contact, the motion detector will act as a backup.
Make sure the control panel has a backup power supply or battery at a minimum. It will provide a few hours of backup in the case of a power failure. You can extend this backup by buying a small/cheap computer UPS system for about $50-100 and plug the control panel into it. The panel draws very little power, so even a small UPS will provide power for an additional 1-2 days. It also provides protection from power surges. If you add the UPS system, do not think that you can forgo the cost of the built in battery backup in the alarm system. Most alarm systems have circuitry to check the condition of the battery. As the battery is discharged, the alarm controller senses this and places a call to the alarm company and sends a power failure alarm. The alarm controller can not detect the condition of the battery in the UPS system, so you will loose this feature if you do not get the built in battery. The way it would work is the power fails, and the alarm system works of the UPS, not even detecting the power failure. Once the UPS is exhausted, the alarm runs on the built in battery. If the outage is long enough and the battery is drained, it will place a 'dieing breath' call to the alarm company just before it's battery is exhausted.
Make sure the alarm system supports both pulse and tone dialing. I ran into this problem when the local phone company stopped supporting rotary dialing and my system couldn't do tone dialing and had to be replaced. Also, the alarm system can be taken with you if you move, and depending on where you are, you may not have the option of what type dialing service you have. Many small/rural areas still only have rotary dialing. There is not cost for this feature, if you think it may be a problem, make sure to ask to see if the system supports both methods.
IMHO, the wireless systems suck. The transmitters that are mounted on each window/door are larger than the wired contacts. They are also more expensive, and you have to worry about replacing their batteries. I just don't think they are worth it, except in special cases.
Make sure that the cost of the system includes installation. This is usually the biggest cost of purchasing the system (except for monthly charges). If the installer is good (make sure he is, before you let them start drilling holes in you house). Get details on exactly how they are going to install each contact and how they will run the wires and make sure it suits you.
Consider calling the phone company, unless you have underground/buried telephone wires. Crooks are now making it a practice to cut the phone lines before breaking into a house. Ask the phone company to move the interface on the outside of the house to the peak of the house and running a cable from the new location. This will make it more difficult for your lines to be cut. You could do this yourself if you are so inclined.
Monthly monitoring costs run $20-30/month. If you pay yearly, you can get a 10-20% discount.