What zone are you in? I think the answer may fluctuate a bit with that info as scapes can be different sizes depending on climate and feeding/watering habits.
I grow FREE WHEELIN but I have also had JERSEY SPIDER and DISCARDED BEAUTY. Out of all of those the tallest was DB and the most consistent with strong scapes was JS. Of course the flower I like the most out of those three is FW...
For me the pro is being able to have something planted towards the back of a bed, especially if it is not really accessible from that side, that will grow and show above the other plants. The con (and it's a big one) is that the scapes may not be strong enough to support the flower and either require staking or they will just flop over.
