I feel Better Call Saul was better than BB. I thought BB as good as it was, was pretty overrated at the time. People were calling it best show ever when it was pretty pulpy and ridiculous at times. I didn't think it was as good as stuff like The Wire, Mad Men, or Deep Space Nine.
That said I really liked it and would like to rewatch it one of these days. I have only seen one season of Better Call Saul so it's time for me to catch up and watch it all at once. 
I agree that BCS is better on average. I think the show really hit a stride until the second half of the last season. Some episodes were a little boring but there was quite a bit of filler in BB.
A "flaw" so to speak that just makes Better Call Saul more interesting - character-wise - than BB, is the simple fact that the premise of Breaking Bad is one of "good guy turns bad". It's even in the shows name. But Walt was never really that great to begin with. He was too prideful to take money from his old partner even when he got cancer and had a struggling family and turned, instead, to making
meth. That's pretty 0 to 100. Right out the gate, Walt is kind of not that great (which I know is the point but still). Meanwhile, Saul, we know who he eventually becomes. We know he's a corrupt fuck in the end. Which makes the earlier exploits of this would be try hard lawyer that keeps failing, and failing, and failing despite no matter what positive he has all the more poignant and sympathetic. Walt instead gives up and decides to make meth right around when he gets a cancer diagnosis. We don't see that slow boil in the way we see Saul's character, who is truly a good guy (or a guy trying to do good) in a crazy world which makes it all the more fascinating to watch.
I truly feel that even the first season of BCS is better than the entirety of BB based off of writing alone. The success in BCS is making Saul is a more sympathetic and tragic figure than Walt is.
Don't get me wrong. Breaking Bad is one of my favorite all time shows but I think there's some kinks that lower it than I would prefer.