I've got the same choice to make, albeit for my insurance rather than for my firm. I'm going to probably go with Southampton (providing Warwick don't give me an offer!) as they simply seemed to have the most helpful staff of the two. Also, Southampton allows you to apply directly for the degree with the year abroad, whilst with Exeter you have to apply competitively during the course, so getting the year abroad is not guaranteed with Exeter.
They both seem to be similarly ranked and well respected, so I'd say that you're best to choose based on the one you liked the most when you visited (you did visit them both, didn't you?) and whatever one seems the best fit for you.