My comments for what it's worth. I'd opt for a Huminbird, Lowrance, or new Raytheon model. Of these I have the most experience with the Huminbird's and can recommend them without any reservations. A few things to think about:
Portability/Ease of use: the Huminbird units just "snap" into their mounting bracket, this motion connects all of the wiring. You probaly don't leave your unit installed on your CC, the other brands require you to attach separate wires for the power and transducer, then attach the unit to the mount by two fasteners. If you attach/remove your unit every trip you'll appreciate the ease-of-use on the H-units.
Transducers: Most models come with 1 of 3 types of transducers; single cone (25 or 55 degree), dual cone (both within the same housing), and multiple cone, which are split into 6 units or more: 1 straight down, others out @ 20 degrees, others @ 40, etc. These units can display a bottom profile in what appears to be a 3D representation. If you plan on doing bluewater fishing over 600' deep you''ll need to go with one of the higher end units for screen resolution higher power. I don't like 3D for SW use. It tries to display the data as if you were traveling in a straight line; fine for trolling, but when drifting I've seen people get messed up in their head trying to figure out what's really where.
Features & Options: I have the speed & surface water temp option on my Huminbird Wide Vison, the largest screen 2D display unit. The speed reads +/- 2-3 MPH of my GPS, depending whether I'm running with or into the current (GPS is speed over ground while depthfinder reads speed through water). I've checked my surface temp gauge to a calibrated laboratory model and it was right on. Frankly, I use this to know when the water's warm enough to jump overboard for a swim more than I do for fishing, even though I log the data periodically. Most units, even the ~$100 models give you depth & fish alarm and some type of "fish ID" signal; which some people like, some don't. The newer Huminbirds allow you to change the depth "offset" so the unit displays actual water depth, depth @ transducer, or depth below the keel - your choice.
Screen Displays: Save the cathode (TV) displays for the commercial guys. Most recreational units are LCD, liquid crystal display. Pixel count is king, the # of dots that make the screen size. I'd opt for a wide screen rather than a tall screen, as the info scrolls from right to left. This gives you more time to read/absorb what's down there. One thing I hated on most units (not Huminbird) is that the depth, temp, & speed data is displayed above the line that the unit is displaying as the bottom. That's right where the fish would be! For example, if your screen is displaying from 0 to 30', but the water depth is only 15', right off the bat you're only using the top half of the screen. Now throw "fish" onto the screen, but you can't see them 'cause they get over-written by the display data of depth, temp, etc. I sent a letter to Apelco (Raytheon) stating that's why I didn't buy their unit & why Bliss didn't move many of them. The newer Raytheon models fixed this (my idea????.
Warrantly/Reliability: Most models are waterproofed to a Federal CFR rating. I used to work @ Bliss/E&B Marine. Huminbird offers a 24 hour turnaround. If they can't fix it in that time, you'll get a new or refurbished model as a replacement. I only know of one Huminbird unit that needed fixing, but routinely used to send other brands back for repair.
IMHO Best Value: Again from experience @ Bliss Marine, if you don't want to spend a fortune, look at the Huminbird Wide 100 (~$100) & Wide Optic models (~$180), there might be new names for 1999. The more expensive of the 2 has dual transducers so it display fish that are straight below the boat as a solid "fish" signal, with fish on either side displayed as a hollow signal. I think the new ones even tell you which side the fish are on. We sold them by the dozens every week and never had a complaint.
That's my opinion - you could easily spend over $500 on a straight sounder, then more if you add GPS, etc. I personally don't like combo units - too much info when you really want one piece of data over the other. Good Luck!