I started diving with a jacket, because it was what I had used in class, and it was familiar. During my first couple of dozen open water dives, I found that the jacket's wraparound bouyancy, combined with the heavy weightbelt I needed to dive thick neoprene in the Northeast, tended to keep me in a slightly head-up position, which caused the thrust of my flutter kicking to direct downward and kick up a lot of silt. Since I didn't want to be the guy ruining everyone's visibility, I got some 2 lb weights, put them on my cam band, and removed some from my belt to help get me horizontally trimmed. It worked well, but the BC's pockets were very difficult to get into with coldwater gloves on, and with 2 layers of 7mm neoprene, I wasn't a big fan of the extra bulk the jacket added when inflated. I felt like the Michelin Man. Also, I started doing some deeper wreck dives, and I got a 19 cubic foot pony bottle. I mounted it to my tank, and thought that that was pretty good, until it freeflowed in cold water and I realized I couldn't reach the valve to shut it off. My buddy got it, but I decided to find a better way, but because of the layout of the plastic D-rings on my BC, I couldn't stage-mount the pony properly.
It wasn't long after that that I heard about a liquidation sale, and I got a great deal on a back-inflate model that I thought was the best thing since sliced bread. It looked solidly made, with stainless steel D-rings positioned where I could stage-mount my pony, and sturdy webbing. It looked like something I could grow with, and I could mount doubles on it if I wanted to. It also had weight pockets, a comfortable back pad, and best of all a removable wing that was supposedly good for singles or doubles.
I found it was much more comfortable to use than my jacket. It fit securely, helped me maintain horizontal trim without having to put weights in unusual places, was much more streamlined (I saw a noticable decrease in air consumption/dive duration as soon as I was used to it), and overall I was very happy with it until I decided to get tech training.
In preparation for my Adv. Nitrox/Rec. Trimix class, I doubled up my AL80s and started getting used to them. It worked okay with the doubles connected through the stiff fabric back of the BC, but there was some minor wobble. Since I also got a drysuit, and was getting used to that, a little wobble turned into a lot of instability on several occasions. The drysuit also meant adjusting the harness, and I found a few things I suddenly didn't like about my BC. First, the chest strap went directly over my drysuit's inflator valve, which was uncomfortable and made it difficult to use. I stopped using the chest strap and found that no problems were introduced by not using it. I also found out that the "sturdy webbing straps" were connected at the shoulder by velcro. That definately did not give me a warm fuzzy feeling. I pictured how amused I'd be if I bumped my tank on something and my shoulder straps tore free at 150'. I started thinking about sewing them in place with upholstery thread.
The weight pockets were in the way too, and I went back to the trim weights. I eventually got everything under control with a little practice, and used the rig for my class. It did the job, but the wing was a little big with a single tank, and a little small with doubles.
Another clearance sale came along though, and I had the opportunity to get a backplate for about $60. I did, since I already had the stainless steel hardware and wing from my back inflate BC, and I rigged up a hogarthian harness. I had a 6 lb plate on my back now, so I didn't need the trim weights. I had the stainless steel hardware I liked, and I could put it exactly where I liked it. I had the sturdy webbing, and there was neither velcro nor stitching to come loose. I didn't have a chest strap, and was glad it was gone. Whether in doubles or wearing a single tank and adaptor, the connection to my plate and harness was rock solid, with no wiggle room. It fit better than any "adjustable" BC I've ever worn, was simple to get in and out of, and much to my suprise it was every bit as comfortable as my back-padded BC... in fact, since it didn't touch my spine at all, and had almost no bulk in front (I didn't need weight pockets, and had thigh pockets on my drysuit for storage), I hardly noticed I had it on. It had everything I needed, nothing I didn't, and was idiot-simple to maintain. I got separate wings for singles and doubles, and I've been very happy with everything about it ever since.
I would have saved myself a lot of trouble and about $700 if I'd purchased a backplate and wing when I started. Of course, some people seem not to like them, so take my experience for what it's worth. Personally, I can't see choosing to dive any other way.