I thought the original Victoria quick reference folding chart was VERY handy with all the economic changes over time. I also love the entire manuel in my hands as I love the smell of new books...odd I know. But whatever you decide I will be buying a hard copy.
A reference sheet, with a MAP ON THE OTHER SIDE! So Awesome.
I'd prefer a nice, big, foldable map (maybe colored by dominant culture or something, or just the 1836 political situation) to a manual. And some kind of reference sheet with techs and/or the production tree (coal makes glass, fruit+glass makes wine; sulphur makes fertiliser, fertiliser (+something?) makes explosives, ammunition+steel make small arms, in the end wine is demanded by POPs, and small arms by military) could be on the backside.
A manual is marginally useful to get printed: seeing as it'll be included as a pdf anyway (and people can thus print it if they want), and it's likely to go old pretty fast.
edit: my decision on whether to get a hard copy or buy online is really dependent on two things: if a hard copy can be readily found, and whether the box will have anything else than the disc&manual (regardless of the form of the latter).