I've had both. The F-250 will tow anything the F-350 will. Although you may need some minor suspension upgrades.
I got the F-350 for the weight ratings. If Ford finds that you are exceeding the weight rating it gives them a reason to void your warranty repairs.
I got the F-350 because with my 5th wheel I would be above the max weights of the F-250. If I got in an accident it would give them a cause of action on me for exceeding the weigh limitations of the truck.
The down side was the F-350 could not be lemon lawed in my state. Only up to a F-250. I found that out because I had the 6.0 in my F-350 and I was stuck with that POS.
I had to add timrens to get my F-350 to tow level, you could do that to the F-250 and get the same result.