In my experience the ipac ones are of much better quality and even though they say ' No Delay ' there is IMO. The ipac one are fully programmable as well but its a long time since i wired mine up. I have one of the aliexpress ones somewhere I was going to do some testing on (A friend gave it to me he had 2 , he built himself a desk one. Well half built anyway ! lol) Oh yeh and they are only 4 button the Ali ones as well.
On a few of my first cabs I hacked keyboards and that worked ok also , But its a pain in the arse so buy one !
Dave.