While there are so many model numbers, once you start exploring, you find that there is a method to their numbering that allows you to pay for what you want and not more than you want.
The 1300's and 1400's are the oldest models with the difference being a four and a quarter inch display (the 1300's) versus a five inch display (the 1400's).
The 2300's and 2400's are a newer set of models that all include some extra features (not game changers in my mind), but still the same pattern. The 2300's have a four and a quarter inch screen and the 2400's a five inch screen.
So your first choice is do you want to pay for the extra features that the 2?00 series include versus the 1?00 series. At the same time, what size screen do you want.
Now as you go up from, lets say the 1350 to the 1370, some features are added. (I am not sure which, but they are things like more routes, European maps included, etc.) Those same features are added as you go from the 1450 to the 1470 or from the 2450 to the 2470.
Finally, if the tag LM is added to a model, then you are paying for life time maps. If a T is added, then you have free traffic monitoring near large cities(but ads displayed at the bottom of the screen when you are not in motion).
Yeah, I realize that this is somewhat confusing, but if, for example, Garmin were to drop the 1xxx models, TomTom and Magellan would eat their lunch in that all the Garmins would be higher priced. Drop the 2xxx lines and they have nothing to offer for those who want the advanced features that they now have to offer. For some travellers, having European maps at a low price (versus what you are charged for adding them later) is important; others have no interest in paying for that.
The best thing to do is go to the Garmin page and use their product search to check off which features you absolutely want. The pick out a few models and do their Compare feature which lists every feature offered and tells you which features the models that you have selected actually have.