Three possible alternatives:

IFPUG function points. If you have to have a standards-based approach to sizing and comparison. IFPUG function points are the gold standard. IFPUG function points are an ISO standard and can be applied to all software types (technology agnostic). The drawbacks for using function points include the perceptions that there is a high level of overhead, counting requires too much information too early in the processes and that only highly skilled wizards can count (or approximate) function points correctly. None of these perceptions are really true, however, in some circles, the tar and feathering has stuck.

Shift the level of abstraction.  Instead of story points, use t-shirt sizing or dogs (or any other non-numerical abstraction) to gauge how much work can be done by a team. T-shirt sizing collapses the discussion of how big a piece of work into rough, small, medium or large categories. Note: When you start to add extra small, extra large and other categories you are jumping back into the false precision discussion. Dogs (or dog points) pushes the level of abstraction even further by equating how big a piece of work is to dog breeds. Irish wolfhounds are big and teacup poodles are really small. No one can equate the same level of precision to dog breeds that they can to the Fibonacci sequence or Cohn’s numbers. Raising the level of abstraction makes it harder to fall into a hole false precision and precision bias. Further t-shirt sizes and dogs really make it hard to do math based on three smalls and a large velocity. I am not sure what the outcome is if you divide a Saint Bernard by a Standard Poodle.

Focus on flow.  Shift to a flow-based philosophy by focusing on throughput and cycle time.   Throughput is the number of units of work (UoW) delivered per unit of time and while cycle time is the amount of time per unit of work. Changing the focus to a flow perspective removes the artificial construct of velocity (average number of story points) and challenges the team to monitor and improve the flow of items they are delivering.

Regardless of the approach, most teams are going to be asked to answer questions that have difficult answers. Questions, like “when will you deliver” and “how much will it cost” are part of the business world. Having an approach that provides answers with the right amount of guidance, without creating the same problems that have evolved around story points is an important step in improving communication and collaboration.