you guys are overlooking the other solution...build 2 cabinets

i have one 4 player cabinet with only 8way sticks, and another cabinet with just a single 4 way stick and a trackball.
playing 8 way games, such as fighters is impossible with a 4way stick. playing 4 way games with an 8 way stick is possible, but generally more frustrating than anything...so if you are set on having only 1 cabinet, here are the options i see..
1. if you have room, install an 8 way stick and a dedicated 4 way stick, you wire them up to the same inputs so you can use either one, but that way you get the best experience on both types of games.
2. if you can easily access the bottom of the control panel, get a 4/8way switchable stick. For instance, a great joystick is the Sanwa JLW, with a slight modification (adding some nylon washers to 4 screws) you can manually switch it from 4 to 8 way pretty quickly by rotating the restrictor plate 90 degrees.
3. If you only want a single joystick, get yourself an Ultrastik360. this is an analog joystick that acts as just about any type of stick you may want, and can bet set to be programmed automatically when the game is launched. it performs very well in both 4 and 8 way modes, however there is no physical restriction. It doesn't really feel the same as a true 4way stick, but it performs very well.
it really comes down to what is most important to you. i used u360s for a while and really liked them, but i missed the physical restriction of a real 4 way stick. i ended up getting Sanwa JLWs for all of my sticks. they are amazing in 4way mode, they have a perfect spring pressure, throw distance and overall feel. they also are wonderful 8 way sticks. they have a square gate to them, so they feel a little different than a happ stick, which has a round gate, but i really like how they feel. and as an added bonus, due to the square restrictor plate, when in 8 way mode, the JLW works great for qbert. the joystick naturally wants to find it's way to the corners, so you just program that game to use two inputs for each direction instead of one.
i personally think that having 2 dedicated sticks is the best way to go, i'd get to JLWs, and set one each way.
if that is not an option then yo have to decide which is more important, the conveneince of not having to switch anything (u360), or the feel of physical restriction (JLW)