I just upgraded my finders this winter. I ended up going with Lowrance HDS 7 touch for the console and an HDS 10 Gen 1 for the bow.
It was alot of dough and I am still recuperating from the expense.
Here is why I did it.
The HDS 7 touch came with the structure scan built in and the transducers too. So, anything HDS after that could be networked and use the structure scan component and transducer of the HDS 7 touch unit.
Then I stumbled onto the HDS 10 Gen 1 at Bass Pro the day they marked them down for clearance to $999.
Originally I had a Humminbird 597 ci HD DI that I bought last spring.
I was going to add another one at the bow. Then I thought about the networking part. So I had almost decided on the Humminbird 798 I think (because they are networkable). But I would have to have a Humminbird hub/switch and cables to get them to network. Then I explored the structure scan of Lowrance a little more and decided on Lowrance. I was going the most economical route and start with an HDS 5......but then needed to add structure scan. I lucked out and had some unforseen bonus income from fantasy football winnings and a couple of other (legal) sources and decided to splurge this one time and bough the HDS 7 touch online with structure scan and then stumbled onto the HDS 10 Gen 1 while visiting the local BP to play with the HDS 5 Gen 2.
If I were you I would buy the most I could afford without putting a bind on my financial situation. Just try to think about where you want to be in the future as far as your electronics go. Maybe spend a little more and buy just one of the better units and get by with it and one of your old units until later when you can afford to buy another better unit. My experience has taught me to get what I want or I will not be happy in the long run. Sometimes I have to wait a bit longer to get what I want. Some things I can cut corners on and be happy and others I can not.
Sorry to say you kind of have to make those decisions on your own.