Any long-duration spell without concentration will be very good. But there are limitations. It's remarkably similar to Animate Dead, actually... but with shorter creatures for a shorter duration.
But first... Unseen Servant was mentioned. Unseen Servant is quite limited if your DM reads it carefully. For many of us it can't do 'anything a human servant could do', rather only the simpler tasks that a human servant would *typically* do. If it's not fetching, cleaning, or serving, it can't do it. For instance, it not only has no climb speed but it can't climb anything, ever... sometimes it can't even climb onto a table. And it can't hook grappling hooks to anything. It might be able to deliver one on a silver platter, but it can't hook it over the edge of a wall. If your DM lets it do more, that's probably why you like the spell.
Tiny Servant is wizard only -- so I don't see how it could replace Spirit Guardians in any way.
Tiny Servant goes beyond pretty much all the Unseen Servant limitations. Even the limitations of Tiny size are mostly mitigated by having a climb speed. But it's worth noting that Tiny Servants can't high jump, not even one inch. It's reasonable to let a Tiny Servant be as much as 2 feet tall (but probably 2 feet tall *after* sprouting legs is more appropriate), and so it might be able to reach its hands 3 feet high... but that's probably the limit. With a running start it can cross potholes, but it'll never make it across a 5 foot wide pit. It might be able to climb out of the pit after falling though.
Also, remember that specific commands take one bonus action each. Having five servants can be very effective if you issue general commands like 'everyone kill the nearest orc' (and watch the wording -- 'everyone attack the nearest orc' will be much less effective). But for doing five different things, such as 'roll up my bedroll and fetch me that lantern, and my sword, and my backpack, and waterskin' will still take five rounds, just like it would if you only had one Tiny Servant.