I like the tadpole design better. Here’s why. On a tadpole the drive wheel on most of the different brands out there is the rear wheel and most will use a 20” wheel. Some have standard or optional 26” or 700 wheels. The smaller the drive wheel, the larger the chain rings need to be to get some speed ( unless you have a IGH and/or a Schlumpf drive). My tadpole has a 26” rear wheel with a 24-38-48 chain ring with a gear inch of about 18-112. This allows me to ride in the mountains and still have speed on the flats using “standard” gears. I don’t need an expensive 65-tooth chain ring for speed. I’m not against a 20” drive wheel as I have a FWD/Flexchain/8spd IGH/22-34-44 bike with a 20” drive wheel. I feel that the drive train is more of a pain on a Delta and most only drive one-rear wheel, which I do not like. Also, I think that a tadpole is shorter and more compact for travel and is lower. I suggest that you TEST RIDE both BEFORE you buy and base your purchase on which bike feels better to you, then start having fun!