sounds like you already have a pretty good plan
to decide which to sell, start by splitting your watches into three groups - definite keepers, ones you dont mind moving on, and undecided.
then, the ones in the undecided pile you can put together in a 'its a knockout ' style face off - grade them in preference, if there are any close ties then put one against the other - ' which one would i rather keep out of these two?'
you dont have to do this in a hurry, you can take your time to decide, so any decisions are not rash
if after doing all this you still only have two or three watches in the 'out' pile, then you know you have a problem :)
good luck