If you want to facetank, Warlord will be the better choice.
That said, if you want to be safer, then Fluffy Squishy Conjurer’s Lazy version would be the best option.
Reason is mostly that with the Warlord, you still need to be wary of things like Grava and can still die if you bite more than you can chew. Also you have no option other than to face tank things since it is a melee build.
Pet builds on the other hand, have the advantage of having Pets be your sword & shield. That allows you to keep your distance from the action and still kill stuff. Ofcourse, since you are reliant on pets, if something makes it past them and to you, you will find yourself somewhat fragile.
And that is where Fluffy Squishy’s uniqueness comes in. The Lazy version boasts permanent 80% phys res, provided you get good rolls on items. That combined with the overly defensive nature of the build + Pets also having 52% phys res (AotG+Em.Presence) = both you and your pets are hard to kill.
That is not to say that Pets > Ret Warlord, however. Since my warlord can for eg: facetank Callagadra while with if you were to try it with Pets, you will die faster than you can blink.
Note: My warlord cannot kill Crate of Entertainment. So if you want 100% completion, or wish to farm Crate for whatever reason, go with pets.
TL;DR- Both are viable, but they do things differently.
Warlord is “in your face”, while Pets are more “I will be here enjoying the scenery while stuff dies”.