If there are mods that are good for everybody, the closest one can get is with the Unofficial Fallout3 Patch. With Oblivion things are different though. I'd recommend the major mods (FCOM ftw!) to anyone. That game has so clear and undisputed problems that the fixes are obvious. Fallout3 on the other hand makes vast gameplay improvements, and the issues with it are much more subtle. After finishing an unmodded (sans UFP) GOTY FO3, i was expecting the major mods to be obvious choises too. Turned out FWE and FOOK2 both have a lot of features and a vision i didn't agree with, and while being quite modular, a lot of stuff i didn't want wasn't tweakable. So i ended up collecting smaller mods here and there and doing the rest myself. So even FWE and FOOK2 with all of their awesomeness aren't for everyone's tastes.
I agree, which is why I made my Realism Tweaks, since I could not get my own game to play out the way I wanted to . . . no matter what mods I tried (and I tried a bunch, including FWE). I designed my Tweaks to compliment all the mods that made the changes that I liked (instead of integrating what others had already done into my mod). Which makes my overhaul very compatible with other mods.
Theoretically, "encumbrance management" could be made into an interesting gameplay feature with backpacks and such that would increase carrying capacity but also introduce some new flaws (reduced agility?). This would make players drop their backpack in preparation for a gunfight, to retrieve it afterwards, so it would just add a bit more of repetitive running around, which (again, imho) wouldn't contribute to a more enjoyable gaming experience. Encumbrance is a very crude abstraction that helps emphasize the combat/stealth divide and keep money scarce. So i don't think it's worth the effort trying to improve on the vanilla FO3 encubrance system, and the only mods that i've seen introduce anything interesting in this regard are the ones that make power armor carry itself. I just don't like the way they're implemented.
Well, I've been working on my own Encumbrance Overhaul for a couple of weeks now and I've finally got it working perfectly (for my own game play style). I didn't touch Agility at all, but created my own Strain modifier (which is much like fatigue, only separate from it).
When you run, you slowly increase your Strain . . . and the higher your encumbrance, the faster your amount Strain increases. When your Strain exceeds 100%, you collapse and lose hit points (based on how great your Strain/sec was). With an encumbrance of less than 60%, you can run for about 4 minutes before you need to rest. At 100% encumbrance, you'll only be able to run for about 50 seconds. You rest when you stop running (your Strain decreases at the rate of 1/sec when walking, and 2/sec when not moving)
When you walk when over-encumbered (over 100%), you also increase your Strain . . . and the more you are over-encumbered, the faster your Strain increases. With an encumbrance of 110%, you can walk for about 2 minutes before you need to rest, but alt 150%, you will need to rest every 30 seconds. You rest by not moving (your Strain decreases at the rate of 2/sec).
Your movement speed is also affected by your encumbrance . . . the more you are encumbered, the slower you move. And this is totally separate from Armor Encumbrance (which my Tweaks increases) . . . so you're not going to run very fast when you're wearing Power Armor. And I disagree that Power Armor should be totally weightless when worn, since this makes PA too powerful, which makes all other armor less useful (My Tweaks reduces the weight of worn PA by 75%; and the weight of all other armor by 50%).