With the utmost sincerity: What is it that you love about Borderlands?
The problem is that I must always describe what Borderlands is like at its peak, when it truly lives up to all that it's supposed to be. This is, unfortunately, not always, and for long periods it's been "not often."
There is nothing quite like Borderlands. For all that Borderlands sometimes fails to live up to its own promise, nobody has ever gotten close to Borderlands. Rage 2 tried to copy it whole hog and was dogshit. Destiny 2 has slowly but surely vanished up its own ass. Overwatch and its ten dozen knockoffs have made half-hearted attempts at its style but never gotten close to the series' charm.
At its best, the appeal of Borderlands is this: serious, meaningful stories that just so happen to take place in a fundamentally unserious world.
The world of Borderlands is stupid. The world of Borderlands is very, very stupid. It's absurd. It's asinine. It's an absolute clownshow. It's Cowboy Bebop as written by the Onion. Everything is either run by corporations or abandoned by them, which leads to the juxtaposition of bright, shining iPod Futurism with Mad Max scavenger world chaos. Everyone has become the most extreme and unhinged version of themselves.
And when it is at its best, Borderlands has the courage to say: okay, so this world might be a truly absurd and farcical place, but what if you actually had to live there? What then? What if we were to extend to this world some suspension of disbelief? What if we were to look at this world we've created and treat it as a place that could exist? What stories could we tell in such a place? How do the unique aspects of our worldbuilding allow us to tell unique stories?
This is what allows moments like the time in Borderlands 2 where Handsome Jack uses Eridium slag to mutate Bloodwing and make you fight her, then when you win, blows her head off with a bomb collar, and treats this as a genuinely horrifying act and a genuine loss of a character who someone truly loved. Then Jack fucks around trying to find a violin, can't find it for like ten minutes and then gets mad when his cruel joke doesn't land, and it's genuinely hilarious, because this is the exact kind of petty, malicious, insecure douchebag he is.
When it works - and trust me, as a fan of the series, I know it often doesn't - there is nothing quite like Borderlands. There is nothing that can quite match the simultaneous absurdity and sincerity of Borderlands when Borderlands believes in itself. I just wish it did so more often.