National Banks product is the most versatile, in my opinion. If you have large LOC, you can split up to various accounts, and this allows you to split up personal and business for tax purposes. Depends which broker you work with, but you can still get a competitive rate on the LOC.
National Bank does have one of the most strictest ways they qualify clients for their 'all in one' (tight debt ratios), but if you can get your maximum, I recommend going for it, before the government makes more rules about HELOCs!