We pack out own too. But there are reasons.
I have a mustache. The rental ones will leak with facial hair. They may even leak without facial hair. A good mask should be fitted to your face. My mask also has a valve in the bottom of it so if anything does leak in one exhale and it's gone. No sufacing to pour it out.
My DW has a prescription mask. No, it was not cheap, but has been worth every penny. She also doesn't wear contacts, so this was the only option for her.
I would also comment on both our masks they have a much wider field of vision than anything I've seen to rent. No impression of looking thru a tunnel.
The snorkel. I will never again use an ocean drinking straw. Which is all an open snorkel is. We bought these.
click HERE This type will close completely off if you submerge it. No ocean water getting in. They too have a valve at the bottom so if you do get any in, which can happen around the mouthpiece, you can push it right back out. They are also so much more comfortable to wear than the rigid type ones.
They also have a treatment you can apply to the inside of the mask and it will not fog up under just about any circumstance. This is an incredible thing. I was completely frustrated by fog the first time I tried to snorkle with the rental stuff.
All of the above we bought from a local dive shop. If you intend to snorkle more than once, it is very much worth it to get your own gear.
As for fins, well, we dont own any. Everyplace we have been will rent just fins alone for a reduced price, and to us it's worth it to just rent them instead of dealing with packing/schlepping them.