Babs has the element of being the first Batgirl going for her. She is also way more "fun", to me. Cassandra and Stephanie are stranger cases.
Stephanie, for example, comes across as an extreme adrenaline junkie who can't stop herself, and even gives up her kid to be able to continue despite having a support mechanism in both herself and her own mother, whom she lives with.
Cassandra, I suppose, is a little more redeeming, but even she is way to grim-mega-dark-Assassin for my tastes though I suppose that is to be expected coming from her background.
For all the accusations that DC is too grimdark, you'd think someone fun loving like Babs would be appreciated.
The problem is - Babs as Batgirl is a very bland character and has been written way better over the last two decades, despite being in the hands of the VERY awesome Gail Simone, who wrote the definitive Oracle Babs.
And DC killed the very good Steph series for an average to below average Babs series, which was in NO way grim dark and not as generic as the current BG series.
DC is very much focusing on their "Superfriends"-characters after they ruined most legacy characters and many fans did not take this well (Connor Hawke, Wally West, Donna Troy --> Got marginalised before the reboot and now they do not exist anymore and characters like Kyle Rayner and Helena Bertinelli, as well as the Batgirls and several others got the short end of the deal).
I understand what they tried to do, but I don't think it works - not when you are known to place very much emphasis on legacies and the past, but very publicly retcon it again and again.
Marvel is much more elegant in the way they use their history - yes Ironman could have possibly had all those wacky adventures and got 3 new bodies and spent time on another planet and has lost at least ten companies, but as long as they don't reference it - and let's be honest, NO ONE WILL EVER AGAIN TRY TO USE TEEN TONY - it may as well not have happend to the current Ironman. Marvel uses "hypertime" without the need to introduce it with a complex crossover that involves alternate timelines and three reboots. DC puts so much emphasis on it's history and the rewritting of it, that fans will never stop complaining, because both the company and many many fans love the idea of ill specified "iconic" characters (man DO I HATE THIS TERM).
Brubaker, Ellis and Bendis rebooted the Avengers to suit their needs around 2004 when you want to put a finger on it - and did anyone really care and ran around crying that reboots suck? No, in most cases fans complained that character XYZ should not be an Avenger or something like that...
LTDR: DC put's to much emphasis on it's history and reboots, instead of giving good writers the chance to write good stories,