There are versions of openmpi compiled with intel and gcc.
We recommend using the intel version if you have no preference, because it should be better running on the intel chip technology present in the machines.
However, if you are likely to take your software to run elsewhere, using gcc is likely to be more portable.
There are many options that can be used when running mpi - please see the manpage https://www.open-mpi.org/doc/current/man1/mpirun.1.php for mpirun options.
Example ///// script <<----- change to slurm
#BSUB -q mellanox-ib
#BSUB -n 100
#BSUB -R 'span[ptile=28]'
#BSUB -R 'cu[maxcus=1]'
#BSUB -oo test-%J.out
#BSUB -eo test-%J.error
#BSUB -J "test"
module add gcc mpi/openmpi/2.1.0/gcc/mellanox