Both these topics have got allot of ink here and the debate still goes on.
To me it's a "no brainer", if your a die hard "hooked deep" fisherman, perhaps the kicker is the way to go, but if your relativley new to the sport, or budget is a factor, I would go with the Trolling plate.
My logic: A kicker cost about 2000.00 to 3000.00, plus proper mounting bracket so you can trailer it, etc. maybe another 750.00 to 1000.00, then you need "Control King".
A Trolling Plate runs from 35.00 to maybe 150.00, only drawback I hear is if you forget to raise the plate it bends and is junk. Well my math tells me you can buy allot of Trolling Plates for 3000.00 to 4000.00.
I bought a new 30" Trolling Bag (had one but didn't know where I put it) I think it was 79.00, turns out I needed two for my application, I found the old one but it was a diffeent size. Solution, buy another 30" bag or buy a Trolling Plate. Jason at Paugus had a Trolling Plate he took off his boat, he sold it to me for what he paid, about 35.00 or 40.00.
This is a little different type than we have read about here, it's "automatic up" and "automatic down", no manual control, speed up, it goes up, slow down, it comes down. I don't know the brand and have never even seen it, he shipped it to my Marina and they put it on.. Works like a charm, trolls at .5 to 1.2, depending on the wind and boat direction. It does take a little playing with the throttle to kick it up to 1.8 to 2.2 if desired, but it can be done.
Otherwise just put it in gear and you go .5 to 1.2 for trolling live bait. Before I was lucky, as my 115 Honda 4 stroke, with no bag, plate, etc. would troll at 2 mph, + or - .5, ideal, but I wanted to go slower for Live bait.
More logic: bags do work good, but most boats need two and it's a pain in the a-- to pull them in each time you want to speed up and move, along with all the other gear,etc. These can be forgotten to be pulled in too, no real damage if you forget, but I suppose it's possible.
Cabelas has a Trolling Plate that is the best of both worlds, not sure which one it's called, but they have one for us guys with the poor memory, it's been mentioned here plaenty of times. If forgotten it will raise itself and also has complete manual control
to raise and lower by design. I think it's about 150.00, still allot cheaper than a kicker.
When it's time for a kicker, it will feel right, "go for it". Until then I would buy a Trolling Plate, either at Cabelas or call Jason at Paugus who can hook you up with the same kind he sold me.