Choosing a roll printer, cannon or HP?

I've had a HP DesignJet 130 NR (24" graphics-oriented roll printer) for a few years now, since they came out. It's not designed for high throughputs really though I have hammered it in the past by printing lots of 5 to 6 metre long electrical schematics direct from Autodesk - it got a bit upset and spat a bit of plastic out.
However it is a good graphics printer for A1 posters and the like, the Mac driver is very well developed and the colour management works very well with Photoshop, producing fairly accurate results without a RIP.
I like HP printers, they've always been very Mac friendly.
No experience of Canon, though.

My experience is with HP. When comparing overall cost of ownership, research ink capacity. (If you were printing PostScript graphics instead of CAD drawings, it would also be necessary to factor in a RIP.) Relatively speaking, HP is more Mac friendly. That is to say there are Mac versions of drivers and software. They also have a separate Mac tech support number. (Though when a product line is dropped, it may be difficult/impossible to get updated Mac drivers.)

Last time I checked, Canon offered Mac drivers but only Windows versions of their poster creation software PosterArtist 2007. But that's an option for the larger format printers.

Though competition is fierce, Canon currently may have an edge over HP when it comes to ink capacity and sheet-fed paper handling. When I researched the two brands, 44" or wider models were considered. I can't stress enough how important it is to calculate cost of consumables before making a purchase.

Agree with you Kwill about the costs of consumables being highly important, but I would add some caveats.
When I first started with large format printing, using a HP Designjet 120NR, there wasn't an HP 24" Roll Format High Quality photo paper available.
I ended up buying in a few rolls of ICI Olmec paper which was a very heavy semi-gloss, however my very ink-dense prints would never really dry properly and these early prints have faded over time.
As soon as the 130 NR came out with its light-fast inks and dedicated Premium Plus Photo Papers I swapped out the 120 and have never looked back.
I would never bother using anything other than HP paper and inks with my printer, its not worth my time.
Whilst I agree that cost of consumables is important, the cost of your time is more significant and potentially damaging to your business. If you can buy a printer that reliably produces great prints time after time and is easy to use then it is perhaps worth laying out a bit more on the cost of consumables.