oh sorry I failed at reading that properly
yeah definately the 70-200 f4L over the 70-300
however might I suggest another track
consider getting the 85mm f1.8 at $400 with a bit of movement of your feet you can cover the whole range of the 70-200 anyway, it's super fast, compact, light, brilliant IQ and you are already familiar with shooting primes
since getting my 85 for use at weddings I use it over the 70-200 most of the time now.
on the crop body its like 120mm which is a decent reach
and down the track at the long end saave up for a used 300f4L IS lenses seem to go quite cheap when they do pop up I picked mine up for $800 on ebay with the 1.4TC this becomes 420 f5.6 with IS i'll post up some pics from this lens at 300 and at 420 later this evening for you
i forgot to add that the kenko TC will also work on the 85mm if you need extra reach from that...