The current leader in the Next-Generation Sequencing world is Illumina Inc.  Offering 5 different scales of sequencing, Illumina provides low to extremely high throughput. 

RTLGenomics offers sequencing on the MiSeqNextSeq, and HiSeq (2500 and 3000) platforms.  Primarily the MiSeq is used for amplicon metagenomic sequencing.  The paired-end sequencing approach allows for up to 525bp fragments (although the chemistry is 2x300, enough overlap is required to overcome lower quality at the end of the fragments and allow the fragments to stitch together).  Amplicon sequencing (and short-fragment shotgun sequencing as well) is more tolerant of fragmented and lower quality DNA than PacBio and BioNano.