Given the option, would you rather buy a chart and get the material and floss together yourself, or buy a pre-packed kit?
As a lot of stitchers seem to do, I've "migrated" from kits to charts over the years. For one thing, charts are cheaper to collect and easier to store! And as I get braver about swapping colors, adding beads, and making other changes to designs, I feel that charts give me more freedom to do so. I mean, I know I COULD make changes with kit materials, but it seems so wasteful!!
I have also found that I hatehateHATE sorting kit floss - especially when it is described only by color (i.e. very light pink, light pink, pink, medium pink....). Small kits aren't TOO bad, but anything with more than 5-10 colors can be absolutely frustrating. And without corresponding DMC (or even Anchor) color numbers, you are totally s.o.l. if you run out of the kit floss.
Finally, most kits seem to include Aida fabric, and I'm not so fond of stitching on that anymore (which is funny, because I used to avoid anything that even mentioned evenweave!!).