Here's what I know (without looking up more information). Sanwa is the preferred brand of most tournament caliber players. It's got the lightest touch of the big name brand sticks, making it ideal for fighting games. Seimitsu is stiffer and more solid, making it great for games like shoot 'em ups that demand precision. Happ/American style sticks are designed for durability rather than responsiveness. If you're the sort who puts his controllers through the ringer, this might be worth considering... these sticks can handle the abuse.
Arcade buttons have different levels of actuation depending on the brand and other factors. This means that some will take more pressure to activate than others. I've got a MadCatz stick for my Playstation 4 and the actuation on the buttons (Sanwa manufactured, I believe) is ridiculously sensitive, so much so that you can't even rest your fingers on the buttons without triggering them. You'll probably want buttons with more of a dead zone, so you'll only trigger them with deliberate taps.