Howdy. yeah both compete very much in the s ame s egment, where things are a tad differenbt between the two "other than the obvious garmin having both touch and a few physical buttons" lays with the transducer
THE gt52hw Is a reasonably good shallow water transducer being 250w, high wide it lends itself nicley to that 0-50mt mark. for your depths however it would start to get a bit funky for deeper waters, the "Totalscan" transducer packaged up with the simrad go series is a picnic basket of existing navico transducer elements.. including their 83/200 khz 300w transducer. having that lower frequency will aid in punching down to that 100mt mark to return a better image.
so whats better........the totalscan would perform better for those depths that you are wanting to fish, however you can always opt to go with a different transducer than the GT52HW on the garmin, say a GT50M-TM transducer featuring a medium frequency 300w that would perform very well in those depths.
Though the big deal would be what you find easier to use. simrad has some very nice features now days with fishReveal etc. Garmin has some excelent mapping options as well. Have a play with both to see what you find easier to use
Moose