What are Approximate Read Counts (Library Sizes) and Lengths (Insert Sizes) for Next-Generation DNA Sequencers? I am performing a simulation study and am curious about the parameters of my simulated metagenome. 

What are the library and insert sizes of some of the most "used" sequencers. Mainly, I am interested in the different Illumina platforms (MiSeq, HiSeq, HiSeqX), 454 Pyrosequencing, and Ion Torrent.

I do not need the long read technologies like Pac-Bio's SMRT and Oxford Nanopore since they are not typically used with metagenomics, yet.
Both of those depend on the application of the library.  For example whole genome assembly of a mammal would require a larger library size than targeted re-sequencing of a virus.  Also insert size varies if you are doing genome assembly a larger insert size is valuable to allow for long range linking and scaffolding.  

I think that if you edit your question of be more specific people will be able to provided a more concrete answer other wise it is "it depends"