that's like picking a boat. everyone has their favorites. I've been running lowrance for over 30 yrs. I also have a raymarine which when it works is great but it fogs up every single time it's turned on for over an hour! factory couldn't find a problem. but it does work great. the toughest part for me would be learning a new product to where I can control it like I want to. just takes alot of time. if you don't have a top/bimini color units can be a pain. I have 3 color units and one monochrome. I'll take a monochrome for GPS ( which you didn't mention) anyday as I can always see it. but color tells you alot more about the structure and fish size than monochrome. you'll have to decide what your expectations/needs are. down imaging? side imaging? how much do you like working with advanced systems. there are dvd's and classes that will help with your learning curve depending on the manufacture/unit you pick.
probably didn't help you any. but just some things to think about.