I've tried several different types of adhesive for my note cards and find I always go back to Duck Brand adhesive. It will produce a more solid line and is stickier than anything else. I used it when making 200 wedding invitations this summer and it was great.
I like this brand of adhesive for the small individual adhesive squares - it allows a clean break when running a strip of adhesive. The hold is good and can be used for cards without danger of the card coming apart.
This is my favorite adhesive for scrapbooking and card making. Very easy to use, use as little or as much as you need and you can always find the bright red dispenser on your desk! Lots of value for your Dollors