Batched or real-time logos
Most of the marketing people tell that, closer to the real-time statistics that they will be able to get, the better will be their campaigns. However, in practice it has been found that the real-time stats will offer too much of variability in order to get more than that of general picture on how the things are doing. .

Standard Analytics
Whatever tool you would like to choose, include standard reports such as
Referrers
Pageviews
Unique visitors and/or visits
Authenticated users
Operating systems
Web browsers
Countries
Domains
Robots
HTTP errors
Entry and exit pages
You can also create the custom reports in order to get the analytics of some specific areas of your website or other customizations.

Tagging Web Pages
For the Web Analytics package, the common way to track put the page is to tag each page with unique identifier. The tag will enable the tool to have accurate information about every page, which is requested and displayed as well.

Tracking via Cookies
Setting a cookie on each customer coming to the site is another common tool for getting the good analytics. This will let the analytical tool to have accurate info regarding the browsers, which are visiting the website.
Scalability and flexibility
In web analytics tool, flexibility or customization is important. The more custom reports are generated, the more you will get out. However, keep in mind that, if you are able to create more reports from the raw logos, then they are harder to build in first place.

Support
If you want to get most out from the tool, you will have to find the tool that gives lots of support. This will be free as the paid or user groups or thought forums support is provided by the respective company.
It might be very much tempting to skip of the paying for initial support plans or installation, especially if have paid lot of solution already. Keep in mind that, the difficult period of adjustment of a new tool is during its installation.

Cost
It will be very much tempting to put up the cost initially in the list of criteria. However, if the business needs are defined from the analytic solution, then you might be able to find that the paid solution meets all of your needs and it is worth its value. Most of the solution available for free come with drawbacks around the scalability, support, flexibility or functionality. Whatever decision you take, remember to include the recurring costs as well.