I bought this thing from Amazon warehouse while I wait for a better deal to come along and you know what? The shape actually works for me, the knurl is decent, and it holds weight!
I won’t update it until I get a deal on a rackable option.
I got the CAP and it’s fine. If weight matters, I usually have 25-30 on each side. I got it from Amazon warehouse with plan to upgrade, but it works fine.
I paid $32 for this one.
https://www.amazon.com/Everyday-Essentials-Olympic-Capacity-CB4S/dp/B0868WQ5TL
on sale for 89 currently
Knurling looks similar to this.
Anything with bearings will have superior spin - why people love xmark chisel. Anything with bushings will spin some, but not as good, but better camber options. Anything 'bolt' will probably be the worst spin, but also the cheapest. ZigZag style aren't as comfortable in some positions and maybe harder for tricep exercises vs some that have the flat/flatter part in the middle.
For spin/good feel I'd go with -https://www.xmarkfitness.com/blemished-chisel-olympic-ez-curl-bar-with-4-needle-bearings/
For better camber maybe https://www.amazon.com/Everyday-Essentials-Olympic-Capacity-CB4S/dp/B0868WQ5TL/ref=sr_1_2?dchild=1&keywords=ez+curl&sr=8-2
I haven't used either of these, but I have the Wright Elite Curl bar, similar to the Vulcan around $150.
Amazon curl bar
Everyday Essentials Olympic Super Curl Barbell Curl Bar, 48 inch (350 lb Weight Capacity) https://www.amazon.com/dp/B0868WQ5TL/ref=cm_sw_r_cp_api_i_PInVEbK76RJ6V