I haven't touched DPPT radar in a bit, but I did BD radar for Castform recently and it was annoying at times. I think in the long run, while DPPT have more rules to follow and you have to pay more attention, being able to get to a higher chain more consistently is more valuable, especially if you're going for multiple shinies at a low encounter rate. BDSP is easier to keep a chain going without having to pay too much attention to the rules, and it has the benefit of having better odds in lower chain levels, compared to Gen 4, but again, if you're going for something that's hard to encounter or you want multiple shinies of that species (like Eevee), you'll want the higher odds, which BDSP makes it significantly harder to get to.
It comes to a point when you get like 3 chain breaks at 0 going for a 5% encounter, it's kinda ridiculous. If I had to put it in a way, BDSP has an easier learning/execution curve but is more inconsistent for getting higher chains, while DPPT has a harder learning curve/requires more attention, but if you understand how it works, you're likely to get higher chains.
Depending on how safe you're trying to play it, it may be faster to get a shiny by resetting at a lower chain in BDSP, since the radar features there set up more ideal radar conditions (universal 4 patches) than it is to build up a chain in DPPt, especially of the chain does break later on, so again, it kinda depends on how much shinies you want and the encounter rate. I haven't done the hunts, but specific hunts like those in the sand/snowstorm routes might be easier in BDSP (compared to DP at least), and BDSP being more modern titles means you have a greater access to shiny hunting resources and don't have to worry about the transfer from an older console. Those aren't direct factors of Gen 4 vs 8 radaring, but I do think they are worth a mention.
