If you have a Cabelas, Bass Pro, etc near you, I'd head over there and just start playing around. See which ones are easy to navigate with using the buttons/touchscreens. I'm sure the Lowrance and Humminbird units don't take too long to get used to; I just felt like I was fumbling around with them for a while and got a little frustrated. Of course, I didn't have a manual to reference either! I took to the Garmin rather quick.
Now, I am
by no means anywhere near an expert...I feel lost most of the time as well, lol. I found a couple of Garmin units that aren't awfully expensive and should provide a nice setup. One thing I've read, and maybe someone can back me up, is that Garmin's "LakeVu" map system may not be as detailed as other map/chart providers, such as Navionics. That's all above my head. Just something I think I remember reading during my research.
Garmin Striker 7SV
Garmin echoMAP 73sv
This Lowrance Elite-7 Ti is one that caught my eye. I was thinking about it pretty heavily for whatever boat we'll get. Keep in mind, to get certain views on various fish finders, you may need to buy better transducers (higher prices). It's also capable of networking to other units/MinnKota motors.
Lowrance Elite 7-Ti
This Lowrance Hook-7 doesn't have side imagine, but is a decent 7" unit that has GPS, 2D sonar, and down imaging. It also has a micro-SD slot that will let you put a map database in it ($$), if you wish...you can spend a bit more for one with the maps preloaded
I think. At $499, not a bad price.
Lowrance Hook 7
This Humminbird Helix 7 SI G2N seems like a nice unit as well. The "SI" means "Side Imaging," and the G2N means it'll be able to network with other units/trolling motor. You can buy most of these fish finders without Side Imaging/Side View, and will be a little less expensive.
Humminbird Helix 7 SI G2N
I listed all 7" units. They seem to be reasonably sized for good viewing, and keep the price at a reasonable number as well. You can go down to 5" or less units, or up to 9, 10, 12" units. Some of the Lowrance HDS and Humminbird MEGA units have darn near photo-like imaging of the floor...it's amazing, you're gonna love it, I promise. /MAGA That may be way more than you need, but it sure looks pretty!