If you are positioned half way between East Dulwich and Forest Hill then I'm sure you will enjoy both town centres. Just because you are a bit closer to Forest Hill station will not prevent you traveling the extra 5 minutes into Lordship Lane for a drink if you choose to. But there is plenty going on in Forest Hill as well as in Honor Oak and Peckham which are also in easy reach of Far East Dulwich.

There is little to choose between East Dulwich and Forest Hill for access to London Bridge, except that when there is any problem with the Southern trains we can head down to the Jubilee line and get home via the East London Line (in about the same time it takes to travel directly). That degree of flexibility is very useful. Of course if you are not significantly further from East Dulwich station then you might choose to use this line instead, offering you a third option.