Dear Theo

I prefer the conical design, because your chance to achieve primar stabilty is heigher, you can drill the last bur only to 3mm and so you can get pressfit in the apical region

the most important thing, under my point of view is to achieve good primary stability, if you are able to get it with conical or paralel  implants, great. 

Both of them are ok, the main goal is to achive primary stability.