Before you start asking questions like that and starting WW111 around here, AGAIN, you should have a look at your application, your customer's standard, local support, local availablity, networks, ease of setting up and using networks, remote I/O systems, and what can be the greatest time saver of all for an integrator SOFTWARE!!! etc etc. My starting point is always software and the I take it from there.
You will find many "disussions" here on which brand is best but at the end of the day you make your own decision. This should be based on a thorough investigation of a criteria list that you have developed.
Another thing you should carefully consider is warranty and service. No good deciding on a brand and then finding out that the local service and repair system sucks.
One item that is invariably not considered carefully is warranty. I am an integrator and invariably I have had the PLCs for up to 6 months, sometimes even longer, before practical completion is awarded on a job. This means that 6 months of the warranty have passed before my defects liability period commences. That is normally 12 months. PLC dies, I cop the cost of replacing it. My favourite PLC maker has a 2 year warranty period in Australia. No arguments. If I use another brand I negotiate with the supplier to commence their warranty at the date of practical completion. If they will not, I then go to my customer and explain the situation and attempt to have the PLC brand changed to a more practical, user friendly supplier. As soon as the originally specified supplier finds out what I am doing, they come running with all sorts of offers, or they lose the job. I cannot afford to use warranty unfriendly suppliers or I would go broke.
beerchug