Octagonal feels like a circle with little ridges in it so you can feel exactly where each direction is. If you want a circular feel but still want a lot of precision i would get an octagonal gate.
Seimitsu and Sanwa are both top-notch japanese arcade part manufacturers. You can’t go wrong with either. Some people like sanwa better, some people like Seimitsu better, its just a matter of preference and opinion. But as i said you can’t go wrong with either. (Although, the mad catz sticks were made based completely off the designs by Sanwa. Its basically a sanwa knockoff, and TE stick uses actual sanwa parts. So if you want your stick to be a lot like the TE version, i would get sanwa parts.)
If the Sanwa LB-30-N Joystick Bat Top is what you also got, from what i can tell, it only fits on the JLW-UM-8. Can be used with JLF series and JLW-TM-8 using an adapter sold on LizardLick.com. – Im not a fan of bat style sticks and cant help you with that much. – It looks as if the JLW-UM-8 stick already comes with a bat-style top, so if im not mistaken, you can just buy that stick + octagonal gate + new buttons and you’ll be set.