Low swr's? Then just strap a dummy load to the roof rack. But seriously...Everything being equal, mounting location, antenna tuning for lowest VSWR, the 102" ~ 108" whip will be the best choice for the original poster's question ......
The 1/4 will never have perfect swr's. But no antenna will. The sweet spot seems to be toward the back of a full sized van or "burb. And shunt will keep the reflect meter from jumping..but that works for any antenna.