Sounds to me like you've got alot of soal searching to do and a hard choice to make. Not knowing someone personally it's hard to give advice in a situation like this. The one thing to remember though is that money isn't everything when it comes to working. It's better to make a little less at a career you enjoy than to make millions doing a job that you hate.
You didn't say wether the sales job was inside sales or outside sales, because the two are very different. Either way, think about your personality when deciding which job would be a better fit. Do you really enjoy being in one place every day (inside sales, the welding job) or do you preffer to be out in the field and somewhere different every day (outside sales). Can you handle dealing with the "public" (uneducated/know-it-all consumer) on a day to day basis doing inside sales, or would you rather be talking to someone that typically somewhat knows the business and is looking for an 'expert' to help them decide what equipment to buy. Or are you the kind of guy that's more comfortable with your shield down and working pretty much alone where you don't have to deal with anyone but 'the boss'?
Personally I've been in jobs that put me in all three scenarios over the years and I can tell you for a fact that dealing with the public is often a real challenge. At the same time the public is in and out so their not nearly as bad as a supervisor who is looking over your shoulder every day that is an idiot......
Once you decide what you need to be happy with the job in that respect, and then factor the money into the equation too, things should be a little clearer.
Before going in for myself twelve years ago, and then again last year when things got bad, these are all things I had to think long and hard about. I much preffer to work outside, in different places, and usually alone or with a very select few people that I know won't kill me with their stupidity. When things are going good I've got everything I need, work conditions that I enjoy, and good money to round things out. Still when things got bad I had to make a choice and in the end I had to give up the freedom of working alone, choosing who I worked with, etc, etc to get a job that payed enough for me to survive. To me the worst part of that was having to stand there, suck it up, and keep my mouth shut and do something 'the hard way', 'the wrong way', and even then spend hours waiting as EVERY decision/project was second and third guessed, etc,... when I knew there was an easier way, a right way, and that the first decision wasn't just the easiest one, the right one, but the only one .... just because that's the way the boss wanted it done. Even worse was to hear how much money they were losing, and knowing that if a job was actually taken on and done the easy way, the right way, etc, etc the first time, instead of going out to look at it four or five times before even starting to do anything, and then second and third guessing the price, the design, etc, etc, etc, etc, that money COULD be made instead of lost. Had it not been for putting up with crap like that I actually enjoyed the work I was doing, and the money was OK. In that case thoug the most important thing was that it was a steady paycheck. Still I knew that there was no way I could continue in that job as a 'career' because the stress levels associated with working with a bunch of idiots was way to high for me to deal with on a daily basis for very long. As it turned out one of the jobs I had was a temp position and I quit it after two months when my own business picked back up. The other I took with a long standing company and after getting their equipment running, getting their equipment organized and inventoried, etc they hired two 'less qualified' guys for less than they were paying me and threw me back out to the wolves. I hit the ground running and as it stands I'm not back to where I was money wise because of the economic mess, but things are starting to pick back up and more importantly I am alot HAPPIER to be back on my own.
In the end, like I said, without knowing you personally it's hard to say which job is the best fit because both sound like they have plenty of perks and benefits. Ultimately it all comes down to what you need to be happy and still make enough money to survive....and only you can make that decision. Good luck either way.