Short answer: If you're going to play one of them, play Borderlands 2. It's pretty much universally agreed to be the best one, and depending on who you ask, probably the only one that's worth going out of your way for. Long answer: The Borderlands games aren't heavy on story, and most of their writing is there to tell jokes. Unfortunately, they also have a certain brand of humor, and depending on whether or not you like that sense of humor you'll likely either find the writing to be extremely annoying, or absolutely hilarious. Personally, I find most of it to be pretty annoying, though there are exceptions. That's not to say that there aren't more serious story moments, because there are, and they're often quite good, but they're few and far between. Between all three of the games that I played, there was only one class that I actually enjoyed, being Gaige from BL2. Every single other class was very [i]ehhhh[/i] at best. The mech lady from BL3 did seem decent from the 5 minutes I played, but I only played 5 minutes. Borderlands is a big open world, but it's broken up into smaller open worlds rather than just throwing you in a big zone and letting you run wild, which is nice. Adds a decent sense of progression which many open world games lack. A lot of the time the open world serves as a place for you to drive your car around and shoot things before you stop at a more linear dungeon to take things on foot, and personally I do like that structure. The level design itself is rarely noteworthy, though. I legitimately cannot tell you about a single dungeon in any of the games because it all just kinda blends together as a series of generic caves and scrappy buildings. If you like loot grinding it does do that well, and that's probably the best thing it has going for it. You can constantly be grinding out weapons to get guns of bigger and bigger numbers. There's a lot of NG+ options so you can keep it going as long as you're willing to play the game, though I could never really get into the NG+ stuff. In my opinion the franchise is, like, [i]okaaay[/i] overall. If I didn't have friends I was playing them with I wouldn't have played any of them, and even with playing with friends, the only one I actually beat was 2. They're fine, but if you're wanting an open world shooty shooty pew pew game, there are better ones out there. I would recommend Ghostwire: Tokyo instead in literally every aspect except loot grinding. Better writing, better open world, better game feel, more memorable dungeons, better weapons (even if you only have a small handful)...

Well, I'm coming to a break from 'D2' again and the other game I'm currently playing ('Alan Wake 2') is one I only get into after dark; for the ambience, you know? So, that would leave a window of game time available until the sun goes down and I might be inclined to try the series out. However it turns out, it wouldn't be as though it cost me anything other than time. I appreciate the candor! 😁