Here's my final take. No matter what brand you go with you're going to get great tools to aid in your fishing adventures. There's things you'll get with a Humminbird unit that Garmin won't have and vise versa. Same goes for Lowrance and don't forget Raymarine (though both of those seem to be a little steeper in price). My advise is to read, read, and read some more to better educate yourself on what 2d,SI,DI, mapping, and record your own maps do.
I've been reading, asking questions, and watching videos for 8 months or so and I still haven't purchased any units. I won't be making a boat purchase and electronics purchase until spring. One thing I can assure you is when I do make these purchases I'll know my boat well and I'll know my fish finders well. There will still be a learning curve for both, but I'll know what I have and at the end of the day the only regret I'll have is that my budget wasn't bigger.
Good luck, and if you have anymore questions just ask.