Porcelain tile uniformity concerns?

Question:im looking for tips about PORCELAIN floor tiles.
I read everywhere they can look like marble but without the maintenance issues, plus it is a harder material.

I like the polished finishes .. and saw some samples of them.. rectified porcelain.

I can't find much info on the net about its shape uniformity, but looks like they are kind of not so squared?

I would like them big.. 24 inches, and spaced at the minimum which i think it is 1/8. But a few persons told me that is too close for porcelain and i should go with marble?

The problem is that marble is much more expensive... so i don't know what to do.

Are there brands of porcelain tiles known for their good uniformity... how should i shop for them.,? i don't know what to look for. please help.

Please do not suggest any other type of flooring... im not interested.
If porcelain is always not uniform, then what would the minimum spacing between tiles be so they look fine?

Thanks a lot.

Answers:
I'm not sure what you're looking at but all the porcelain tiles I've seen are square. All square. Very square. There should be no uniformity issues whatsoever. Go to a home improvement store and take a look.
The tile type really has very little effect on spacing. However if you want 24" tiles I would suggest 1/4" grout lines at least. It will be extremely difficult to maintain a straight even grout line If you go 1/8". Imagine, if for some reason one tile was out of square a little or slightly offline (which does happen) the grout line would disappear completely. The grout would also be more likely to break if there was any movement in the floor.
If you insist on 1/8" spacing, it can be done, but the results will be almost definitely poor.