Typically there are 5 types of flooring: Carpet, vinyl (tiles and sheet goods), Laminates, wood and ceramic (or porcelain).

Read here:http://www.biggerpockets.com/forums/67/topics/51308-porcelain-vs-ceramic-which-is-more-durable

https://www.forbes.com/sites/petercarbonara/2017/08/22/buc-ees-game-of-porcelain-thrones/#26e4d9237626.

The property has been paid off for many decades and has been exquisitely maintained.

Home Depot has a some great porcelain 12x24" tiles for under $2 per sq. ft.

I would suggestion latex modified in most cases, especially with porcelain ...

The trimming is lousy, wall boards bounce, large gaps...detail is horrible.In NYC i could get a total gut job and have installed: Proper sheetrock & durock wall backing, a new shower body with single lever handle & spout, porcelain floor tiles throughout, porcelain wall tiles surrounding the tub to ceiling height, tub, sink, new vanity, baseboard, prime and paint and 2 light fixtures for 10-13K. 

I don't have a problem spending a bit extra on nice porcelain tiles and stylish looking finishes if I know it means I will attract more of a 'higher classed' tenant, and giving me a higher rental return.My renovation will take a month and I plan on:-Gutting out the flat, removing the carpets and parquet flooring Knocking down the wall between the kitchen and the lounge Installing new kitchen cabinets with a stunning island, AND A BUTLER SINK!

I'd be tempted to pour a ~4" flat slab with plumbing run before pouring and then do a dry mix mud pan just like a shower over it and do some small porcelain tiles. 

So maybe a light gray stone/travertine porcelain.