There are a lot of things to consider, more than the number of channels you need. If you're totally new to the area of audio production, you may want the services of a professional engineer. If you'd rather not spend the money on a consultant, then at least talk to a knowledgable sales person. My recommendation is Jason Koons at www.Sweetwater.com because he's the guy that's giving me real world comparisions on some very expensive gear.But my advice is to buy something that will give you great sound and has more of everything than what you need now. Plan for the future. It's cheaper to do it right once, than to redo a half-baked job twice. Plus, it's work and sound better.
We just updated our main mixer and are in the process of getting a new one for our recording and radio broadcast studio. We got the Midas Verona in the 64 channel version and we're getting the Allen & Heath GL3300 for the studio. We were using Mackie 32-8's in both places previously with sidecar attachments.
The quality of the Midas is far superior to the Mackie. However, you need to balance the cost vesus sonic quality. Soundcraft, Allen & Heath, Yamaha and Crest also make great sounding mixing boards. The various models have different features. You need to determine your needs and wants before you go shopping, otherwise you won't have a guide to indicate whether a particular model would suit your needs.
We run a large band and choir and we have live amps as well as stage monitors with various mixes. Our adult services are contemporary and our youth services are rock concerts, each with it's own different needs. We record audio and video and pipe it into our closed circuit TV system so the whole building can hear what's happening in the main sanctuary. So the board we would need may be entirely different than what would work best for you.
In conclusion, write out specifically what you need it to do now and what you would like to have it do in the future. Then call someone, like Jason Koons at Sweetwater music, and talk to a sales person who has hands on experience producing music. They will be your best source of information on all the different brands and models.