The WSM is the easiest smoker to learn. It's one of the most efficient of all smokers. It's extremely well built. It requires practically no tending. They're very portable. They make excellent small grills. People who move up to big deal smokers usually keep their WSMs. It's a bit of a pain to clean up. It's really too small to do a good job with ribs. Other than that, it's easily big enough to feed 12. Like any cooker with a small firebox, it's very sensitive to bad wood; and it's quite possible to oversmoke with it.
The performace characteristics of ceramics like the Primo, the Big Green Egg or the Kamado are similar to the WSM. The major distinctions are: They are way too heavy to be considered portable. They rank among the best grills -- at any price. They last damn near forever. They are relatively insensitive to cold weather. You can buy your way around some of the WSM's size limitations, but it WILL cost you. The Kamado, if you can afford it, is yard art -- a real wife pleaser. The Primo and BGE not so much.
Small offsets are cranky. They require tending, and until you learn their ways, they require nearly constant tending. Most of them are poorly constructed. They have a rather steep learning curve, requiring four or five cooks just to be confident of your fire building technique. Without charcoal baskets they go through fuel quickly -- 30# to smoke a brisket. They're also sensitive to bad wood, and can overmoke. Although you can grill in them, they are not good grills -- their small diameters put the charcoal too close to the food, and the top too close to your hands. Most require a few modifications (4 hours, $40) to run decently. Add another couple of hours and $20 to get them running well. In fact, a Bar B Chef, Hondo or Silver can be tuned to run as well as a Klose. The LOOK like barbecues. You get a lot of grate space for your buck. They're large enough to handle ribs. Properly modded and tuned they can turn out product equal to anything. They're easy to clean.
Of the small, inexpensive offsets, the Bar B Chef sold by Barbeques Galore is the best by far. The first four hours of major mods are already done. The tolerances are better. It's built of 12 ga steel. Next the Hondo Pro. Then the Hondo, NBBD (do they still make them?) Silver Smoker and SNPP in a dead heat. After them the Char-Grillers. I put the Char-Grillers so far down the line because they were already drafty before Char-Griller put the ash drawer in. However, they can be tweaked to work as well as any other 16 ga. smoker.
I owned an unholy combination of a Hondo and NBBD for 15 years. I ran a WSM at work for a few years. And I've been around a few Silvers and Smokin' Pits. I"m not pushing the Bar B Chef to validate my own purchase decision. I'd done a lot to inform myself, before I bought it. But the truth is, I hadn't decided which smoker to buy before I dumb-lucked into it. I'd bought an "as is" Bar B Chef Texas Charcoal Grill that could not be made to work, and the Offset ended up as part of a very complicated deal negotiated to get a Texas that did work, but still preserve the discount.
Ceramics excel as do it alls. So does the WSM. If you can live within its size limitations, it's the smartest purchase. But, let's face it, it doesn't look like a 'q. If you must jump into that little patch of hell known as small offsets, the Bar B Chef is the most rewarding.
Good luck,
Rich