I started on a WSM and have made 3 UDSs. Both are great.
UDS wins on cook time, cost, and if you like the dry heat.
WSM wins on portability, simplicity (you just buy it!), and if you like wet heat
Honestly I'm pretty sure you can cook on anything as long as you can control your temp well. Many people use a kettle and do well. Best of luck!
18.5" WSM (Model #2820)
Used Lang 48 or Meadow Creek TS60 or Klose being hunted for so if you know of any PM me