My general-use build for a [Panzer Vulpaphyla]. I like [Tenacious Bond] as a fairly universal buff and easy recovery condition for companions. You could always try to slot another bond in as a general-purpose buff that works for many builds and objectives (Config B, linked below, is probably the best contender for an alternate general-use build), but some extra utility is my pick for a general-purpose build.

Mod Breakdown

[Viral Quills]: mostly present for spreading Viral status, but does some minor damage which synergizes with other mod choices.
[Martyr Symbiosis]: the Panzer dies for your sins, but don't worry you can bring it back with [Tenacious Bond].
[Panzer Devolution]: halves the recovery period for your companion, and lets it continue to spread a little viral while you bring it back.
[Hunter Recovery]: the quills and spores they spread will provide a constant source of healing with this mod.
[Primed Animal Instinct]: enemy and loot radar are always welcome. Flex slot for other builds, for general purpose this is fine.
[Bite]: to give us the prerequisite stats for [Tenacious Bond]. Only needs to be Rank 4, but if higher gets us more healing from [Hunter Recovery], why not?
[Synth Deconstruct]: all enemies damaged by the Panzer's quills will have a 25% chance to drop a health orb. Great with [Equilibrium], still useful without.
[Tek Assault]: it might not be hard to bring the Panzer back, but a 60% chance to ignore death helps with buff uptime and saves you some effort.
[Tenacious Bond]: gives you some free crit damage and lets you bring the Panzer back faster by getting headshot kills.
[Fetch]: turn off the part of your brain that worries about missing any loot drops.

Mod Explanations

The order of the precept mods doesn't matter too much since there's only a few of them, but this is probably the optimal priority. Otherwise, not much to say here.

Other bond mods can of course be flexed into similar builds, but I don't personally find the bonds not covered by this and the below builds to be very useful on Panzer. In some cases, the mods don't seem to be worth a slot, but mostly they just seem more fit for specialized companion builds. Panzer is a good fire-and-forget companion and my go-to when I'm not using a companion tailored to my current Warframe, but doesn't really do anything super build-enabling like, for example, a primer [Diriga] can.

Alternate Builds

CONFIG B: Reinforced Panzer, to get a free boost to fire rate.
CONFIG C: Seismic Panzer, for bonus efficiency on channeled abilities.
CONFIG D: Tandem Panzer, to get some free combo counter.