An arcade stick is a controller that often comes with a joystick on the left and buttons on the right. It can make many fighting games easier to play.
The moment you realize that the Neogeo Arcade Stick Pro is good both as a console and as a standalone fightstick is the moment you realize that SNK created a great piece of equipment.
The PXN-0082 can be considered decent compared to its competition within the category of mini fightsticks.
This is a budget controller that is available in many variations and is a decent option if you would like to try hitboxes.
The Fighting Stick seems to be a sort of prototype for other Hori fightsticks such as the Fighting Stick Mini and the Fighting Stick Mini 4.
Ipega has graced the fighting game community with a mini fightstick, the Ipega-9136, that is even smaller than the standard mini fightstick, and it does a great job at this novel type of product.
The Martial 5in1 Arcade Fight Stick is yet another white-label arcade stick, but it may capture your interest regardless.
The Yusha Fight Stick is a mini fightstick that was specifically designed to dock the Nintendo Switch.
The Arcade-C-1P is a fightstick with the simple goal of running Raspberry Pi games while packing nifty perks, such as built-in speakers.