Neither is best. Each has its value. Both fly well.

Slo-V is RTF / slow stick you have to build
Slo-V comes with everything / Slow stick you have to figure out the parts.

Slow stick, because you have to build it and because you have to pull together the radio sysetm, is also more flexible as far as what you use and what you can change. But is its also more expensive to get it into the air.

Each has its value. Depends on what you want.