Both are reviewed in pc pilot jan/feb 2006 issue (out now)
i'll tel you the comments in the at a glance section and leave you to buy the magazine or make up your own mind.
Just flight 707 professional-At a glance-panel and performance issues detract from what is otherwise an absorbing simulation of one of the great classics of passenger aviation. 2 problems that i can see at a quick glance are small guages in the 2d cockpit and a stripped down overhead panel in the vc.
Cessna caravan-at a glance-quality of the cockpits 2d/vc are a huge improvement over fs2004 default versions.
I can see that you also have cargo so probably a virtual cabin and can open doors to the cargo pod and a cargo door on the cessna.
Have fun flying with whatever you choose