[en] Based on the cold fusion reaction valleys, referring to the minima in the potential energy surfaces calculated on quantum mechanical fragmentation theory, some of us and collaborators suggested the use of a ⁸⁶Kr beam or its neighbouring nuclei in their very first publications of 1976-7. More recently, one of us (RKG) and collaborators stressed its use again in 1993-4. In view of the very recent experiments, reporting the use of a ⁸⁶Kr beam for the cold synthesis of the Z=118 element, here we have re-investigated this problem for a large number of Z=104-120 nuclei. We find that the use of a ⁸⁶Kr beam for cold fusion reactions is as appropriate as the Pb and Ca nuclei and the optimum targets are ¹⁷⁴Yb, ¹⁸⁴W and ²⁰⁸Pb, respectively, for synthesizing the ₁₀₆²⁶⁰Sg, ²⁷⁰110 and ²⁹⁴118 nuclei. The ⁸⁶Kr + ²⁰⁸Pb is the reaction used in the above-mentioned Berkeley and GSI experiments. For other elements, lighter than Z=118, the ₃₄Se beam is found to compete with the ₃₆Kr beam, whereas for Z>118 elements ₃₈Sr is shown to be a natural choice. ₃₂Ge and ₄₀Zr are found to be more suitable for the production of neutron-rich isotopes, thereby requiring the use of radioactive nuclear beams. The radioactive nuclear beams (and targets) are predicted to be of great use for many other nuclei. The role of ₈₆Kr (being similar to the doubly magic ²⁰⁸Pb or ⁴⁸Ca) is perhaps related to the recently predicted strong shell stabilizing effects of ⁷⁶Kr in cluster decay studies. (author)