David
I too prefer good old magnesium carbonate. My favorite is the block form (I haven't noticed a difference between brands), which usually can be found for a better price if you look through retailers who market to gymnasts rather than climbers. I'll list below the different kinds of chalk and grip aids that I have experience with and the merits/demerits of each; hopefully you'll find it helpful!
CHALK
Block Chalk: My personal favorite. Good coverage, lasts a long time between chalk bag dips, and feels nice and grippy.
Superchalk: Sold by Metolius and several other companies have variations, comes loose in a ziplock-type bag. I'm not sure what the additive is, but I find it really fluffy and it doesn't coat my hands (backs especially) the way I want it to. It does help though and it's better than nothing.
Eco Ball: To me, the eco ball doesn't do a whole lot for grip. It dries my hands well, but I feel that my grip almost actually gets worse. It almost feels sandy.
GRIP AIDS
Rosin: Hardened tree sap used by dancers. I love rosin, but I don't use it for climbing because I feel it gives me TOO much grip. If regular block chalk doesn't do what you want, this will definitely give you more grip. It needs to be warm to be the most sticky, so breathe on your hands or rub them together. I would be careful with rosin: with too much grip you can increase your risk of flappers.
Liquid rosin: Liquid rosin is made by dissolving the hardened rosin above in alcohol. It's extremely sticky when first applied. I feel that the stickiness is lost very quickly and my hands end up feeling almost sweaty.
Tough Skin: I believe this product is marketed as a temporary adhesive for applying foam prewrap before taping a joint. I've used it as a grip aid and it is sticky like liquid rosin, but doesn't loose its stickiness quite as quickly. I still get a wet, almost slimy feeling though, so it's not my favorite.
Hope this helps!!