What you saying is a total generalization. There are joysticks that are better for shootem ups, 3D or 2D fighters. Different lenght of handles, or tops (ball or battop), shapes of rotation (square, round, diamond, octagon).
Some have longer degree when it engage than others, different springs etc etc.
I did some research on joysticks. Now I'd like to find some more on other parts
Better and preferred are two different things. I prefer square restrictors over round, regardless of the game. Some people swear by round restrictors because of the fluid motion. I have wico 8-way leafswitch sticks in my top gunner cabinet. I am not a big fan of them all that much- I will probably end up switching them out with a pair of wico microswitch bodies. Some people look to the wico leaf joys as the holy grail of all joys.
There just is no clear-cut "best" joystick out there - it always boils down to preference.
This is the same with buttons. The most common button in arcades is the concave happ pushbutton. They also make a convex button, which some people absolutely cannot stand. Some people like them better for fighting games (tactile response, or some BS like that). Once again, personal preference.
Spinners- Each has its benefits and drawbacks. Different arcade games used different spinners. Arkanoid had a geared spinner, Major Havoc used a roller, Omega race sometimes had a pot based spinner. It depends on what games you are wanting to play that will determine what kind of spinner you want. That being said, the new TT2 spinner is the standard bearer (IMO, of course) due to its high resolution, small footprint, and neat optional accesories.
Trackballs - Yes, the Happ trackballs are usually considered the best performing of the lot. Betson makes a cheaper trackball, but works quite well too. The GGG Ice trackball has a lighter ball, and some people say it plays a little differently. All that being said, preference comes in to play as the biggest decision maker. Do you want a flashy trackball with changing lights? Are you on a budget? Do you want no frills high performance?