I replaced my mirrors within a few days as I just couldn't get on with the factory version. Especially on the nearside. I went for the round stainless steel ones from Librands, primarily because they work, but they also look better.
I have also seen a round version supplied by BHM which have "angled" stalks which seemed to have even greater articulation.
You will read on this site that some members had difficulty fitting replacement due to some aftermarket brands having a 10mm stalk where the factory fit 9.5mm. Some even having to cut the seals to fit!
Don't panic...........
1. Make yourself a brew
2. Pour an extra cup of hot water and put all washers and seals into the cup
3. Enjoy your tea
4. Easily fit your new mirrors with the softened seals
Have fun safely,
Tony