it is best to use buds for strength but there is alot in the whole plant in oils and fallen trics etc, most people use trim as it has alot of trics and is basically waste after harvest if they dont make butter or hash.
strength wise it goes bud>trim>leaf>stalks, so if youre making it out of only leaf you will need alot more meaning it will taste a lot more, so with bud you need less it will taste comparatively better. also there is different ratios of thc to cbd all over the plant i think the fan leaves have alot more cbd and are recommended for a more medical effect.
the last two times i made budder i made bubble hash first with the plant material shredded then threw it in a pot and made budder with it. very strong taste but no waste. the bubble bags for making the hash took out most of the crystals but even after that it was strong enough to knock me on my ass.
if i had mountains of bud to spare id use only water cured bud for best effect.
(those wet plants i was talking about were some i had to harvest and freeze i was unable to dry them and they had very little bud on them anyway.)
its all upto you with taste as the limiting factor imo. some people wont use anything but trim/bud but others will use every bit of it.
if you are worried about taste definately look into water curing, alot say they only makeedibles with water cured buds etc as it leaves very little taste. i will be doing that next time i think.
invest in a huge pot for this.
also look into oil, flour, milk, booze, glycerine there are lots of ways to do this find whatever suits how long it has to last and what you would be cooking.