Radix trees are great, with the right workload. The main competition (for strings) are the ternary search tree (for sparse keyspaces with rare insertions) and

Radix trees are great, with the right workload. The main competition (for strings) are the ternary search tree (for sparse keyspaces with rare insertions) and the B-Tree (which is nominally disk-optimized, but that optimization also tends to help with the L3 cache). None of those are best for all workloads. There are situations where using a radix-tree is actually faster than a hashtable with a good hash function, and situations where it is slower than a red-black tree.