There are several different types of mixers available. Some people believe that you have to have a Bosch mixer to make bread. That is not true! The mixers that I am familiar with are Sunbeam, Kitchen Aid, Braun, and Bosch. I have also seen Cuisinart and Viking mixers. After searching the web, Sunbeam and Brauns are no longer available.
First, decide how many loaves of bread you want to make each week. I can make three 8x4 loaves in my Kitchen aid 4.5 quart model, which holds about 6 c. whole wheat flour. Upgrade to a larger capacity if you wish to make more loaves.
Second, decide how much power you need to use. 250 watts is basic, good for white breads, rolls, and wheat bread made with half white flour and half wheat flour. If you want to make your breads with all wheat flour, look for a model that has a higher wattage. I have seen wattage go all the way up to 800 watts of power. If you want to add attachments to your mixer (grinders, slicers, blenders, etc.), look for the maximum wattage your budget will allow. My first Kitchen Aid, due to the design (holes in the arm where excess flour can reach) and trying to mix all wheat bread dough for 10 min., caused the motor to overheat and catch on fire. Yes, that's right, it caught on fire! As I had the mixer almost a year, Kitchen Aid was really great to send me a new mixer right away. The newer models that have larger bowl capacities do not seem to have this problem.
Third, consider how heavy the machine is and where you will use it. Watt for watt, Bosch makes the lightest 800 watt machine vs. Kitchen Aid Artisan & Professional series machines weigh a TON, making it a permanent fixture on your counter top.
Last of all, consider your budget. I would love to get the top of the line Bosch mixer, but at $400, it is out of my reach. I have had my Kitchen Aid for 15 years and it has served me well. Remember, this is an investment...ask for one on your birthday or Christmas wish list. Also, I have found great bargains on KSL.com. So, ask around....you might find an "orphan" mixer in need of a new owner!