I second the S-glass. If you are just getting started laminating (patches, repair, or kitesurfboard construction) I would recommend:
Resin Research epoxy (UV stable)
6oz (actually 5.6oz) S-glass
That is the best bang for your buck. And you really do not need anything else, except mixing tools & cleanup supplies.
The only way E-glass is going to save you money is if you do SUP boards or very large lay ups.
Carbon "looks great" but is pretty useless for anyone who is not already experienced with glass layups and the next level - vacuum bagging.
Kevlar requires you to buy shears and bury it with glass AND keep light from getting to it (paint over it) - PITA with only some return on your investment - but it does make a slightly tougher board than S-glass.
3.7oz S-glass just seems like a waste for kitesurfboards. Though it could be useful when used for prone surfboards where light weight is valued over long term durability.
6oz S-glass is just so all purpose, easy to work with to get it right, beginner friendly, and high durability, that you really can't beat it. Kevlar is best for deck patches only.