I cant advise which to use. I use humminbird due to success with them and not with the Ray Marine I purchased. I hear people love Ray Marine, but I got burned by them once with the Dragonfly product. Whatever you do, do not buy a Dragonfly. (discontinued anyway I believe)
Connectivity / Compatibility to my minnkota also drives my humminbird choice
Things to consider:
GPs color mapping is a must. It makes getting back to your honey holes so easy i would never go without it again.
Map card is a must. They are all similar enough for popular inland lakes so dont overthink it. Remote lakes... well I cant speak to that but I hear there isnt great coverage for those by anyone. Also, using the generic maps that are included with any model are useless in my opinion.
To actually see fish you only need sonar. Chirp is nice, but surface clutter isnt an issue unless you are in shallow water and in shallow water a locator is hardly any use. (i.e. the cone is too small and doesnt cover any area)
Down imaging is hardly used to find fish, it is used for finding/verifying structure. You can find fish with down imaging but it is significantly easier with sonar. You can however get clarity of your sonar returns once over the structure to clarify what is or is not fish. I never use down imaging any longer as I have side imaging which gives my pretty good structure feedback. I used it on rare occasions but wouldn't miss it if it were gone as long as I had side imaging.
Side imaging. Great to see fish off to the side. BUT, it takes practice to recognize fish unless they are a school of fish or larger fish such as carp, large walleye or pike/musky. For example. I took a 16 inch smallie on my line and ran it past my side imaging back and forth directly under my boat and 10 feet down, while the boat was not moving. On a 9 inch screen it was a noticeable white fleck. As in if it was 70 feet to my left or right, it would still be noticeable but only as a very small fleck with a correspond "imaging shadow" on the lake bottom a certain distance away (the distance of the shadow tells you the height in the water column).
Touchscreen. Again not necessary. However, here is where it wins. If you are running multiple screens and moving quickly over water to find fish (not on plain but moving quickly) those fish will arrive on screen and quickly scroll off screen (depending on depth and speed of course). If you run a split screen and use the map as one part of the split screen and one of the imaging options as the other, its great to have a touchscreen to be quick on the draw and select the most advantageous screen for marking the fish. For example I run a map, side imaging, and sonar all at the same time. If I am not directly watching my locator and already have my screen "selected" that I want to mark with, it takes too long to click buttons to get to the correct split screen and then move the cursor up/down/left/right to select the fish, or structure you want to swing back around for. Its my only regret is not buying a touchscreen.