<p>I've got both versions of the 50mm (W and ULD) and like both, I haven't used the 65mm much so far, the 110mm and 210mm APO are also both great.<br>
I think it would depend more on your style and preference:<br /> - do you like a big foreground or big sky or exaggerated perspective - Get a 50mm<br /> - do you like a more natural feel - Get a 65mm</p>