Southern Prides. I've owned 4 of them so far. I also used a nice Sherley offset alongside the SPs at my original location. If you use a southern pride correctly, and use the same wood you're using in say a big offset, the end result is almost indistinguishable. On busy days I'd be serving brisket (and other meats) that come off the offset and SP and you really couldn't tell which was made on which.
Don't get me wrong, there are plenty of people making bad BBQ on rotisserie machines. Just like there are a lot of people making bad BBQ on old stick burners. So you still need to know what you're doing to some extent. But the beauty is you don't have to tend to a fire (oro hire someone you trust and have high labor costs) constantly.
If you have the space at your location to run offset pits, and you don't mind working the pits all day everyday yourself, or have the money to hire someone who can cook your level of BBQ for you, then that's certainly a good way to go. But if you want to do volume, or don't have the space that regular pits require (don't forget wood storage space), investing $15-20k in a commercial smoker will ultimately save you a lot of time and/or labor, save you a ton of space, and if done right, produce very consistent product.
There's no right or wrong answer, it just depends on what you want to do, what your physical location limitations are, and making the best of it.
For example, I'm now right downtown at this location and there's just no room for the Shirley or other pits at the restaurant. So, we built a platform and hoisted an SPK500 up on it at the back of the kitchen. Have to work with what ya got.