Pro wieldless: cheaper
Con wieldless : rubber washer will fail at some point in time
I wouldn't use it as a turkey fryer or anything where the heat is over 212*F
Pro wielded : should last forever
doesn't have any problems with hi temp
Con wielded: cost more if you can't do it yourself;
Ask the guy in the wielding shop if he'll trade for some homebrew.
Do what you like!
Brew what you like!