working for a rather large out sourcer my team looks after pretty much every San/product vendor, think we're currently above 5Petabytes total.
Now adays with such large controller caches and ssd tiering almost any vendors can provide the performance that all but very large implementations require. The real differentiators are arround support inc firmware revisions , speed of access to 'skilled' techies etc, and extra functionality replication/backups/application integration . Please remember a new storage array is not a panacea for all your storage problems or requirements the actual San wether fc or network has to be closely looked at inc s/w stacks on servers , bandwidth/queue depth on ports or ISL's.
From a personnel opinion overall for most installations I prefer Netapp , the flexibility they can provide cannot really be beaten , though it's still not right for every situation and it all generally comes down to who can give the biggest discount.
But always get free training units thrown in no matter what the vendor you go for , as its generally easier to get some freebies before you place the PO.
On a final note make sure you get the a good historical performance tool in place wether from the vendor or a 3rd party, so many times in my career I've had people complain about performance , but they have no way of monitoring or capturing performance apart from real time, this makes life hellish trying to fix issues.
Man I really hate typing my than a few words on an iPad, blah .