I think it is pretty well accepted that the Efiles manufactured by KUPA are the best in the world (and it is not just personal preference when choosing an Efile either).
There are important things to consider like speed, vibration, types of bits, whether the efile can go in alternate directions, variable speed etc. It's not just which works best for you but which works BEST.
Responsible safe efiling needs to be taught ... it is not efiles that hurt people it is people who hurt people .... so learn with a provider that teaches you safe responsible efile techniques.
An efile can be very useful for certain jobs and although your goal is always to sculpt the finished nail with your brush, you won't be doing that from the start so an efile could come in handy when debulking and it is certainly handy when debulking for a French rebalance!!