Depends on what else is being used in the house and if there are any plans to change to quartz/granite in the near future. Also look at what is popular in your neighborhood.

I think it's worth going with stone. Have you looked into Corian options? There are a lot of colors available. Also the seams can be sanded and won't be visible. Marble is a nice option as well.

The porcelain tiles are a good choice, very durable and low maintenance. While marble is pretty, I would go with quartz because there is no maintenance. You are doing this for yourself, not your neighbors, so get what you like, not what is trending. Stick with neutrals so you have the option to change up the accent colors as time goes on...

Go porcelaine for floors not ceramic and as for counter I think the amount of radon emitted from such a small piece would not be any worse than the chemicals used to make manmade products.

You can get premade vanity tops (often with sinks) in granites and marbles that aren't very expensive, so it's worth looking into. Specific choice matters less than how all the parts work together, so make sure your choice coordinates with the tiles, paint, and so forth...

There's a lot of pressure to use quartz, granite or other stones, with the attitude that everything else is less than.

Laminate may not be a great choice for today's bathrooms, but acrylic solid surface is a good option. Check Wilsonart's web site, their selection is terrific. They will send you samples for free, something none of the others will do.

Are you trying to keep existing vanity and just change the top? We bought a Silk Road vanity with travertine double sink vanity from Overstock.com the price was much less than trying to get a 6' cabinet and separate top.

In the Pacific Northwest are, the majority of the home buyer's expect to see slab counters (granite, quartz, or solid surface) or at least tiled counter tops in master bathrooms. If the master bathroom remodel is done nicely with slab counter tops, it will add value to your home when you go to sell. Studies done in this region say you will acquire 100% back of your investment from a master bath remodel, kitchen's you will recapture about 125% of your investment. Check with a local realtor in your area to see what they recommend for you neighborhood.

Quartz countertops can be quite beautiful, given the right vanity (this one is at 15% off too)