what are the pros and cons of each.  minus the side imaging.  thats out of my price range.  paticularly on a unit to mount at the drivers console

The main advantages that the Humminbirds have over Lowrance right now are at the same price points Humminbird usually has higher resolution, more power and a dual beam transducer. All of these make the sonar better and are important features on the water. For example, compare the 787c2 to the Lms-520c.  Both cost $649. The 520 is a 20 degree cone angle transducer, 2,400 watts power and resolution is 480x480. The 787c2 has 20 and 60 degree cone angles, 4,000 watts power and resoltuion of 640x480. You will find this comparison to be true at almost all price points.

Its pretty much Ford vs Chevy, Minkota vs motorguide, Lowrance vs humminbird.

Its all about personal preferance. the two seem to have comperable units in every price range.