I see a lot of people down on maxsonics. Ill tell you I have seen a lot of different brands of maxsonnics in action and they do what they say they do. so I personally dont feel they are that bad. as far as the auto turn on goes that is what the remote is for. It would be different if you werent already having to run wire to the back, but since you have to anyway I dont see auto turn on as that great of a feature. just IMO.

kicker does make really nice amps but as a company as a whole I am not overly impressed with them. I personally feel it is more branding then anything else. I do love my phoenix gold amp. I have never owned anything else phoenix gold but I can say the amp is worth the money. as far as sundown goes they seem to be a bit pricey. I have never owned anything sundown but from what I have read online and those people's system I have seen with sundown I was not overly impressed (I realize that it could be the person who set it up that caused this).

not saying maxxsonics puts out a better product than any of these three companies. just saying for the price it isnt terrible and the price difference between these is pretty big.

 

This is what I went with, Alpine X-Power MRX V60 amp, and a Audio control LC6i added to my stock HU.
It was a very good choice

 

I like Audio Control products, they have some nice OEM integration pieces that add tuning capability.

PAC-Audio offers a plug-and-play interface for adding an amp (remote turn-on and RCA outputs) and includes matching harnesses so you don't have to cut any wires.
David Navone Engineering offers some of the highest quality LOC's on the market.

MTX, Alpine, Rockford Fosgate, JBL. JL Audio, Audio Control, and a few others, offer OEM integration pieces with a wide variety of options and features. Factory HU retention is very common these days.

when adding on to a factory system, getting both wire harnesses (into car and into radio) allow you to get the signal without cutting wires.