Yes, general crappy uniques are worth saving simply for the crafter recipes--as Dave Simmons mentioned, flip them at your crafter for the treasure chests and use those to upgrade all of your vendors until they are maxed. Then use the 4x or 3x unique swap for relic stacks, or whatever. The 5x unique recipe for an Any Hero unique used to be good, back when a lot of those rando any hero unique drops were considered good (like the Energy Rifle or Apocolypse armor), but those are pretty much trash and fodder for the exchange recipe. The only good any hero uniques now are the ones that you get from event vendors with special currency (and you can endlessly roll them for best stats before you buy it), or very specific bosses in game with extremely rare drop rates.
bear in mind, it has to be identical uniques for those recipes, so they can quickly pile up if you don't have enough storage space.
Good cheap storage is the hero-specific stashes, because you can load those up with any hero uniques (and of course that heroes unique) and any insignias, cores and a few other items that the specific hero can use. Bear in mind that you can't put unlocked artifacts in those hero stashes.
Urus...I would just keep a few of them around with a decent selection because they will always drop, and players tend to just leave them out randomly for people to pick up. The defense armor is the best overall, and generally axe, fist, bow are the only other ones that you would use (mele, physical, ranged, I think). For most mental-based toons, I think the Armor uru is preferred because in any of those mental heroes, the mental damage you can pump out of their skills, omegas, and gear is a bit excessive and most of them are lacking in defense. The Armor uru is actually either 1st or 2nd tier on all heroes, probably. Just remember to replace the level 25 uru with the level 50 one when your hero levels--and yes, you will have to add a new runeword to it.
Pro-tip: for leveling, you probably only ever want to use River of the Soul on those level 25 Urus because it really helps the leveling process. Most heroes are seriously spirit-starved in early levels, so it helps tremendously. Also, it's incredibly cheap and after you've piled up your runes (yes, you should keep an entire stash for runes, if you can), you should be able to craft it infinite times--at least certainly more than you would ever need.
And if you ever think to start spending money on this game, stashes are key, and those hero packages are generally pretty good as well: you get the hero, alternate costume, hero stash, and a set of fortune cards, xp pots. --and those packages offered through the MH store are different than the ones you get through Steam. I recall the MH store hero packages offer better items compared to Steam.