It's all on personal preference. I love Duncan hines Classic White - I think it's delicious, but I'm not crazy about their French Vanilla. Some people swear by their butter golden recipe, but I've tried it several times and think it's, well, nasty! On the other hand, I absolutely love BC's French Vanilla and it's primarily the only one I use anymore, unless I need white or chocolate for something. BC used to make a dark chocolate that was delicious but I can't find it anywhere, so I've been using their Triple Chocholate Fudge. Personally, I don't likeDuncan Hine's dark chocolate. I never noticed a height difference between them - maybe I should look out for that! But I always, always, always get compliments on the BC French Vanilla.
Also - I've used both kinds for 3D cakes and never had a problem. Once I tried one of the "doctored" cake mixes to supposedly make the batter denser for the teddy bear pan - but his neck ended up cracking and his head fell off - a problem I never had while using a regular cake mix. So who knows.