I actually think that the pulldown could well be better than chins/pull ups for building muscle.
I realise that might be considered quite controversial but I do have my reasons. Lots of people have trouble engaging their lats, there's been a few threads here about it, and I think the pulldown is better because it's easier to pause and squeeze in the contracted position, and really slow the negative. Back muscles really seem to respond to a good squeeze and a slow negative. Backs also seem to do well with a higher rep range, like 12-15.
To do that doing pull ups would mean you would have to be VERY good at pull ups. How many people do their pull ups with a pause in the top position and a 3 second eccentric? Not many, and even fewer are doing it for sets of 12-15.
Just my musings, but I know that I did chins for years without much growth in my lats at all (although I got ok at doing chins I guess...), and since switching to pulldowns my lats are growing much faster.
Also, the soreness I got from chins/pull ups was always in my teres major. I dunno if that's worth considering, just thought I'd mention it.
convinced me for the pull downs
about chest dips - any chance they could be replaced by anything other than push ups? i HATE push ups... being perfectly honest, being able to do many chest drips is a personal dream that i really wanna accomplish.
and if i HAVE to do pushups, what kind? elbows go sideways? or downward? do i do wide? close? diamond? (that is, assuming there is no other solution except push ups)