You'd need to search up info on each specific barb you find. They have different properties. They're not all equally peaceful. Some are potentially better but they require certain things to make them efficacious. For example either seconal or secobarbital (I forget which) is really short acting so you would need assistance to keep it flowing into your blood stream in order to ctb with it. I think IIRC it was used as a preanaesthetic.
I think Phenobarbital (sometimes confused with pentobarbital due to the similarity in name) is one of the longer acting ones. I've seen it mentioned for use in a multi drug combo but never saw much convincing argument for it's use. Certainly not over N.
Some of the stuff sold on DNM's isn't as advertised too. I'm watching a couple of vendors who recently claim to be selling powder N. I'm expecting it to be a dead end but one of them has sales of their other chems so we'll see but even I, or anyone else, were to take the risk it would still need to be sent for testing. It's not a short term solution situation unfortunately. I always look for it on DNM's because its my preference and it has been aeound before but honestly I'm not sure if we will ever legitimately see it again. Doesn't hurt to scope out the possibilities though, right!?
There used to be a fair few barbs but very few are available now. The ones that are don't really provide the same kind of bus pass as N. I think the opiods are a better alternative. Protonetazine and the likes. There's a few analogues like that which are considerably stronger than Fentanyl, though the ROA impacts just how much more potent. IV wins out every time of course and if that's not something you're comfortable with it might not suit you. Not that other ROA's wouldn't work. They're mostly slower I think. I'm still uncertain on whether they'll make it through customs these days too. They tend to come from China. If you can get them domestically they'll probably be cut with something to bulk them out and maybe to add nuance to their 'high'.