Question: I am looking for some advice on getting LVP installed. We have an area of about 2000 sf where we want to install LVP. The area is currently a mix of flooring consisting of a mix of tile, laminate, and carpet.

We will hire a professional installation company to do the job and 2 companies recommended removing all the old flooring for the new installation. One company, however, suggested installing OSB planks over the tile and then installing the LVP on top of the OSB in order to reduce time, dust, and dirt as well as money for the tile removal!

I am very confused now about what would be the better and most lasting option! Any advice is highly appreciated.

Answer: 
This comes down to opinion based on preferences for time, cost, current flooring conditions, etc. Here's mine.

This sounds like a company looking for a quick-n-clean job with max profit. You'll have areas of floor higher than others. You'll have base trim and door casing issues to address. Also, tile can be skimmed with leveler. It's not necessary to overlay it, but that's probably the installer's preference out of laziness or greed.

I would drop all contact with that one. They sound sketchy, like the window replacement outfits who leave you with smaller windows because they don't want to take out the existing trim and reinstall it so they just fit windows *inside* it.

The best solution is usually to strip everything to the same level of subfloor and carry on as if the home was new.
With multiple types of flooring being replaced with LVP, the only 2 companies you should be dealing with are those that recommended removal of all the old flooring. DO NOT consider one that recommended OSB over the tile. Throw away their business card as well.