I genuinely can't tell the difference between genuine Canon inks and the ones I get from Inkredible, Khandro. With genuine inks costing £66.49 but third party ones costing £15.54 (for a full set of five, in each case), I'll be sticking with the third party ones. (Although I can often go for long periods without using my printer, there have been times when I've got through three or four full sets of inks in well under a month. That can mean a couple of hundred quid difference in the price of the inks for that month!)
What I am fussy about though (and what, in my opinion, makes FAR more difference than the brand of inks used) is the quality of the paper that I print on. For regular documents I only use 90gsm HP Premium paper. For most photo prints, I use HP Everyday Glossy Photo Paper but for prints that, say, I'm framing as gifts for friends, I use Kodak Ultra Premium Photo Paper. I never cease to be amazed by people who swear blind that they can tell the difference between different ink brands but who then buy their photo paper in Poundland (or similar) and wonder why they don't get great prints!