Have gone thru allot of smokers in my life. From large off set stick burners to the Weber Smokey Mountain charcoal smoker. If you are just looking to do a few fish once in a while you can't go wrong with the "Little Chief Electric" smoker. They work great for fish.
If you are going to do a bunch of other things like beef,chicken and what not, the big trend now is either the automatic pellet smokers or the big dollar "Egg" smokers.
Just depends on your demands.
I was into competition BBQ and spent allot of money on different smokers. Texas Brand smokers are fantastic but pricey.
I am now retired from all that and its just the wife and I now. A few years ago I bought a Weber Smokey Mountain charcoal "Bullet" smoker and I couldn't be happier. I did get the 22 inch size and feel it may be a little big for what I need,,but once in a while I can load it up with multiple racks of ribs,brisket,or a bunch of chickens!
I have owned a "Little Chief" electric smoker for over thirty years now and it still performs great! I have loaded it up with about six to ten trout depending on size, and smoked them all day. They turned out great, I use Hickory for fish, but apple wood works out good also.
One rule I have always followed,,never smoke fish on the Meat smoker. Use the smaller smoker for fish. If I am doing larger cuts like Salmon,, I'll use the Weber kettle bbq and cook it on a cedar plank.
Again,, this is just what I prefer,, your demands may be different. Some many variables when it comes to this topic.But if you are just starting out,, You cannot go wrong with the Little Chief Smoker for fish! Good luck and Happy Smoking!