Where are you located? It may be that in your region they only offer 2cm...although since it's engineered/man-made you'd think it wouldn't matter. (Granite, for example, is usually 2cm thick on the west coast and 3cm on the east coast.)

With 2cm, you might need a plywood subtop b/w the slab and your counters like you do with natural stones (granite, marble, etc.) - but I'm not sure.

I would check with a fabricator/installer to see what the actual installation differences are b/w 2cm and 3cm.

If you do need a subtop, then ask how they handle the exposed edges.

I'm in Louisiana. I know that most people around here use 3 cm with granite and there are some other quartz brands that offer it. I'll definitely ask about the exposed edges. I'm a little concerned that the 2 cm will just look too thin, but can't find a lot of pictures to compare.

The granite in my 2003 kitchen was 2cm. It did not seem to make a difference functionally speaking, but it did look less substantial and cheaper than 3cm. You may want to find out if they can do a mitered edge so it appears wider on the sides. Also, if you are doing a slide in range you will want to make sure the 1cm height difference doesn't pose a problem.

We just had our kitchen done and went with 2 cm quartz. The way the countertop guy explained it was that with 2 cm you need a plywood subtop, whereas with a 3 cm you don't/can't.

If you are planning on having an undermount sink, it might be a good idea to have a plywood subtop. That way the sink can sit between the plywood and the countertop, and won't need any additional reinforcement. Without the plywood, you would need to use brackets attached to the countertop to support the sink weight, which sometimes are not enough.

For us, having the plywood also helped us bring the countertop higher so that it would align with the garden window sill.

A miter edge will give you a thicker edge detail.

Would another store perhaps match Lowe's price?

Personally, I love the thicker counter top and would keep looking ... you're going to have these counters for a long time, and you don't want to be "almost happy" with them.

What's that saying? The bitterness of low quality remains long after the sweetness of low price has been forgotten. (Not that 2 cm = low quality, but you know what I mean.)

With mitered edge, even with the 2cm stone you can have thicker edges.

I am a fabricator.

2CM or 3CM is typically a regional preference. In many areas 2CM is almost always laminated so the edge looks like 4CM (if it's done well).

I do both in my shop but 2CM laminated is actually more than 3CM due to the additional shop labor so most customers opt for the thicker material as it looks more substantial than 2CM. Also, with 2CM laminate the sink cutout is not normally laminated so the thickness of the material is evident even with a nicely laminated or mitered edge.

Either thickness provides a good countertop given the limitations of the properties of the specific material.

Full plywood underlayment on 2cm isn't necessary or a good idea. Perimeter strip underlayment is more dimensionally stable and plenty strong.

I am not a fan of plywood holding sinks in either. Plywood is incapable of applying constant upward pressure on a sink as straps on sinks do. And replacing the sink would be a nightmare.

Have your fabricator do a test of a built-up edge before ordering the more expensive miter. It may look better since the seam is out at your waist instead of up at your eye.