<p>I have two options - to buy either the Ender 3 or the Mega Zero. I'm heading towards Ender 3 because the Mega Zero doesn't have a heated bed. </p>

<p>My question is, how is a printer without a heated bed (the Mega Zero) a better option than one with a heated bed (the Ender 3)?</p>

<p>Why would I even consider buying a printer without a heated bed when the Ender 3 can do the same things <strong>and</strong> has a heated bed? I want be able to print not only PLA but other materials as well. Doesn't the Mega Zero limit you to using only PLA?</p>

Lack of a heated bed does not necessarily limit you to using PLA. I would say (among those I've used) the material that's least sensitive to whether you have a heated bed is probably TPU. Depending on your model, it can even be hard to print PLA without a heated bed, unless perhaps you're willing to use a brim or raft. Printing ABS or ASA without a heated bed is almost certainly out of the question, and PETG
might
be possible, but I'd expect it to be difficult.
Mechanically, the Anycubic Mega Zero looks very similar to the Ender 3. The claimed bed size on the Mega Zero is slightly smaller (220 mm vs 235 mm) but they might just be counting the usable part.
The only possible objective advantage to the Mega Zero I could find is the double gear extruder, which may help with printing faster or flexible filaments.
Presumably you could add a heating element to the bed if you want.