Spirit Walk is a skill that fits into a category that I like to call "Panic Button". These skills can have other uses, but they're generally skills that are very good at getting you out of a bad place.
The Witch Doctor has a few other ones.
This will pretty immediately clear the space around you of enemies. It will give you a few seconds to catch your breath and set up for the battle to continue. If you rune it for 100% bonus armor for 8 seconds, that will give you an additional boost for 4 seconds as the battle continues. Alternatively, you could rune it for move speed to help you get out of there as fast as possible.
If you are being chased by only one enemy, Hex will immediately chicken that enemy and allow you to catch your breath and get some bonus damage in. You can heal up and space yourself appropriately while he's a chicken so you can be ready when he comes back into his normal form. This particular tactic was the only way I was able to beat Izual on Hell difficulty solo. For some reason, Izual can be chickened, although I don't think any other bosses can. It's also particularly effective against rare monsters.
Grasp of the Dead
You need to either rune this for 80% slow or reduced cooldown for it to be particularly effective as a defensive ability. Both of these are solid choices, but the 80% slow against any enemy without the Fast affix is as good as just stopping them outright. This is very effective as a pre-emptive panic button. If you see a huge horde of enemies running at you, retreat to a choke point and cast Grasp of the Dead to prevent them from coming near you.
The Fetish Ambush rune will get you out of a bind quite effectively. You spawn 6 fetishes, each dealing 250% weapon damage in an area when they spawn. This will usually kill everything in your immediate vicinity, and then you will have an army of meat shields to help you position yourself properly afterwards.
This passive will save you from death once, but it really works best in conjunction with Spirit Walk. If you're using Horrify or Soul Harvest, however, this can definitely be a viable choice even without Spirit Walk.
Ultimately, however, Spirit Walk accomplishes multiple things at once, which none of these other spells do. Out of all of these options, none have the sheer utility of Spirit Walk. I recommend, if you insist on not using Spirit Walk, using at least two or more of these other abilities. I actually use Spirit Walk, Grasp of the Dead, and Hex most of the time for maximum survivability, and I still occasionally get cornered and have nothing to do but maximize my DPS before I die. Spirit walk is really, really good.