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It's important first to understand BLPM motors. There are several types that operate in a different way and some very good text books on the topic are Hendershot & Miller (2010) or Hanselman (2004).

If you deal with radial flux BLPM motors, anaytical packages such PC-BDC (SPEED) can give you very good results for surface PM motors, while for interior PM motors FEA is absolutely necessary, e.g. PC-FEA which is embedded in SPEED . Most of the finite-element packages will give you similar results, difference is made in price, computation time and easiness of usage.
Last, but not least, thermal aspects in BLPM are usually neglected even though magnets will demagnetise with temperature leading to higher current and lower efficiency for the same output. FEA will fail to give you a good estimation of the motor thermal behavior being capable of modelling just conduction. MotorCAD can solve the thermal problems and is linked to SPEED.
For axial flux motor you will need to go into 3D FEA. There are several analytical approaches developed at various Universities worldwide.

There are a lot of subtleties to designing BLPM motors, some not immediately obvious, particularly if you want an IPM motor with wide field weakening or something. It is often easy to get something that will do, but hard to get a really good design that is high efficiency and maximizes the material. FEA software, even ones with front ends for entering geometrical data, will have more limited options and gives one answer; the time it takes to vary parameters and formulate an effective design can be very long. SPEED is a spreadsheet entry package with many powerful design options and routines, It is by far more sophisticated than any of the FEA packages in terms of design variety. RMXpert is simply an FEA bolt on.

The correct procedure is to do the electromagnetic first-pass design with SPEED and then link into thermal analysis using MotorCAD. Then once a design is formulated it should be cross-checked with an FEA simulation. SPEED does actually have an FEA bolt-on that is now available through the distributors, or you can use a different one. However, all this can take time, and you need deep pockets to buy the packages. But if you want to do a proper job, you need to buy the right tools.