First thing is a good book or resource on canning for the 21st Century ... the Ball Blue Book of Preserving
is cheap (about $5) and the standard text ... but, they have a new expanded edition (with more recipes) out called the Ball Complete Book of Home Preserving
(about $14). Of course if you want to sepend some time online ... there is the National Center for Home Food Preservation
- which is sponsored by the USDA .... and free.
As for which canner pot to get ... the first question is what kind of stove-top do you have? If it is a glass/ceramic cooktop ... read the manual that came with your cooktop ... or call their user information line. There is a limit as to the weight they can support. If you have a standard electric stovetop - you may not be able to use the old standard pots used on gas stovetops - you need a flat rather than "wavy" bottom - and for big pots you may need to upgrade to a heavy-duty burner element.
As for a preference in "pressure canners" - which can also be used as boiling-water canners, or pressure cookers ... I prefer the All American line
because of how they are made - but they are more expensive initially than some others. Less expensive, but still good quality, is Presto pressure canners
... but you have to replace rubber gaskets every year or two ... (these links are just for demonstration of what I'm talking about ... you may be able to find better prices elsewhere on the net or locally ...)
FYI - pressure canners can be used as pressure cookers (often called pressure cooker/canners) - but pressure cookers can not be used as pressure canners unless they specificaly say they are dual function. A pressure cooker/canner can not be used as a pressure fryer (to make homemade KFC).