So backing down from a five page essay here, I’ll just say the gameplay variety is insane. Single-player first-person shooters are pretty much all I play, and whenever I leave Borderlands, everything feels boring. I maximize the variety I get out of the game with eleven characters across all classes with completely different builds/pets/action skills and weapon allegiances) with a rule that I have to use all red-texted gear (so I rotate through them per character whenever I pick one up for a new playthrough). This combined with the volume of story missions, side missions, challenges, Dead Claptraps/Crimson Radios/Echo/Eridian/Tycho logs, and other stuff to do means that the game is very different every time I play.
For example, today I may play Zane with only Atlas weapons (specifically: four that I didn’t use the last time I played him), with a Clone/Drone build (as opposed to the MNTIS/Barrier build on my other Operative), using the Shockerator and constant Clone swaps (out of several different combat styles I have for him) on a run through the Tazendeer Ruins where I may make a run to catch the CoV Radio.
Tomorrow I may play FL4K with only Tediore weapons and a Rakk/Spiderant setup in the Devil’s Razor helping the B Team lock out some CoV. Then Vladof Moze with an Iron Cub build in the Handsome Jackpot clearing out a Scraptrap nest, then maybe Zane with Atlas again but a different weapon set, different combat tactics, and on a different planet.
With 65* different maps and 11 characters, that’s 715 different ways I’m playing. I won’t count the different missions/challenges as unique, but each character also has anywhere from four to seven different combat styles, which brings that to somewhere north of three thousand different ways I hit the game. I use the difficulty slider to make these as viable as I like (some builds/weapons don’t do well at high Mayhem levels, where some steamroll MM11, so I just adjust the difficulty to match). It will be a very long time before I find the game repetitive.
*I don’t count Arms Race because I don’t get to use my unique build/loadouts, so it just adds 1 to the total above, and I don’t count the Heck Hole or the Cartel hideout because they’re seasonal.