I'll offer my voice in favor of the Chessex mats too. I've used a variety of other erasable maps over the years and we always come back to the vinyl Chessex one that has held up to nearly twenty years of gaming.

I have a massive selection of dungeon tiles and other scenery, but the erasable battle mat gets used probably 60-70% of the time.

I have a couple of other brands of mats that I've picked up over the years, but they've gotten somewhat stiff due to age. I'd really recommend spending the money for a good Chessex one.

As previously mentioned wet erase only (mine still has a clover a guy doodled on the corner with a dry erase marker over 10 years ago), and avoid leaving reds on the mat. If left on too long (multiple months), even black can be a bit troublesome to remove.

Another surface I've seen used for an erasable battlemat is a whiteboard that had the grid lines drawn on in permanent marker. There are other pluses, as they're easy to hang on the wall for storage (or even play) and are typically magnetic too.