Why are type II restriction enzymes the most commonly used restriction enzymes in molecular biology research?

Restriction enzymes are enzymes that can cleave DNA molecules at or near specific bases. Type II restrictions enzymes are the most commonly used restriction enzymes in molecular biology research because of their ability to recognize stereotypical sequences and produce a predictable cleavage pattern. 

Type II restriction enzymes recognize and cleave the DNA at specific, fixed sites with respect to their recognition sequence. This creates reproducible fragments, and distinct, predictable cleavage patterns, which is useful for a wide range of molecular biology applications such as DNA fragmentation and gene cloning.