In a situation where you are developing a caching solution that needs fast retrieval and insertion of key/value pairs but also needs to maintain insertion order for iteration, which Map implementation would be most suitable?

For a caching solution requiring fast retrieval, insertion, and maintaining insertion order, LinkedHashMap is the most suitable choice. It combines the features of a hash table and a linked list, allowing for constant-time retrieval and insertion while also preserving the order of insertion. HashMap offers fast retrieval but doesn't guarantee order. TreeMap orders elements but has a more complex structure. Hashtable is outdated and should be avoided.