So I cooked that Butt on what would be considered a bottom-end gas smoker. It works well, however accessing the water dish and chip dishes is a pain in the ass that requires careful disassembly mid-cook. I can do it in 5 minutes, but that's still lost heat and wasted time. Whatever you get make sure the chip dish/tray has easy access without losing too much heat.
Electric is totally set it and forget it, however I'm not sure of the economics of use electric heat for long a duration to heat a poorly insulated metal box outdoors. Gas is very economical, and pretty simple. Once i get the settings fine tuned for a smoke sessions it stays pretty steady, though you do need to monitor and make fine adjustments as needed. This is where a wireless thermometer comes in handy. DO NOT get a horizontal smoker or a grill with a smoke chamber. They suck. A grill is for grilling a smoker is for smoking. Something like below is a good starter smoker in my view. Separate door to access chips and water, multiple racks.
Amazon.com : Masterbuilt 20051311 GS30D 2-Door Propane Smoker : Patio, Lawn & Garden
I do however use a good thermometer setup, as the built in one is garbage. (literally off by 50 degrees) Wireless is super convenient so you can be free to game/watch tv/etc. while something cooks for 6+ hours. 2 probes is also necessary so you can see internal temperature of your meat AND the ambient temp inside your smoker.
Amazon.com : Maverick ET-733 Long Range Wireless Dual Probe BBQ Smoker Meat Thermometer with Larger Display and added Features - Black : Patio, Lawn & Garden
Even better. Combo of that smoker with a wireless thermometer.
Amazon.com : Masterbuilt 20051311 GS30D 2-Door Propane Smoker with Cuisinart Thermometer : Patio, Lawn & Garden