I buy the cheap flat ones off ebay, I’ve bought them for four cars over the last couple of years, and the only ones that were rubbish were a different design, a metal strip along the spine rather than the plastic/rubber type, the metal strip just resulted in squeaking and juddering. Put up with them for a whole summer but replaced them for the winter.
+2 for the rain-X. Bought the combined window cleaner/rain-x bottle two weeks ago, even in heavy rain and loads of spray over the last couple of days I never needed the wipers on constant, in fact they never came off the slowest intermittent setting (about 25 seconds). Going over 45mph the droplets just run off, when going slower it doesn’t seem to matter how much water builds up, you can just see through it. The only exception is on single lane roads with lots of approaching traffic or where there are lots of streetlights, the light reflecting off the droplets is distracting and does reduce visibility.