I would suggest following the internal chronological order as set out in the Wikipedia entry:
Neal Asher - Wikipedia
I started with the Ian Cormac series, then went back to read Prador Moon and Shadow of the Scorpion, which provided essential back fill. I've read the Technician (much improved writing over the prior books!) and am starting on the Transformation series now. I am not excited about Spatterjay series from summaries I have read, so unsure if I will read that series.
Seems like Line War jumped forward in time w/o resolving all the characters, so hope for another book or two in that arc. Also The Technician cries out for another book or two.
P.S. It'd be nice if SFF supported a spoiler tag as some other sites do where detail could be discussed but hidden from casual display.