Hi
I personally rate Mer car polish as it is long lasting and appears to have protective qualities. Mer is not the easiest to apply but as it seems to last longer, you won't have to apply as often.
Auto express have rated Turtle Wax Plantinum Extra Gloss as long lasting and easy to apply, rating it better than Mer. But I sometimes wonder if some publications prefer larger brands, who perhaps spend more on advertising.
huckster