The one you fish with the most
That's entirely dependent on season and species. I'll give a brief overview off the top of my head.
I got a 6'6" medium heavy and a 7 foot one piece ultra light for summer and canoe fishing.
I have a 9' medium heavy and a 10' medium for chucking heavy lure for bigger species, salmon, musky, etc.
I have 2 fly rods, one for bigger fish one for not as big fish (sorry the fly rod weights are still unfamiliar to me because I don't fly fish near enough).
I have 2 beater rods, a 6'6" and a 9' to loan friends. I have one downrigger rod for when I get out in boats.
Onto the bulk of my fishing, winter Steelhead and river run salmon. I have 2 spinning float rods, a 10'6" and a 13'6" depending on a) the size of river I fish and b) degree of Bush around me for casting. The 13'6" I sometimes use for bottom bouncing or still fishing in bigger rivers.
I have a 9'6" ultra lite trout rod for small creeks and to small spinners. I have a 10'6" medium for bottom bouncing, medium lures, and is my most versatile all around rod.
Now my favourites

I have a 10'6" Fenwick centrepin float rod. I use this for medium rivers or when I do a bunch of bushwhacking, but mostly backup. My favourite rod I'd a 14' custom tied Raven IM8 centrepin rod. It bends in a full loop almost sometimes, tons of hookset power, and great sensitivity for the light hits, with enough power to horse em in from big rivers. These guys I interchange my islander steelheader reel for, my next big purchase will be a nicer centrepin reel.
Still missing a bait caster. My spinning reels are such crap though that I'd probably be better off upgrading those first, I can do whatever with a spinning rod that I would with a bait caster. Could also use a nice dedicated musky rod, but I don't go fishing for them enough.