my experiences of NEX5 with:
SEL18200 - the only E-mount lens I use. It's big, but not heavy, so I carry it in case I'm too lazy for MF or need the wide/zoom versatility. IQ is good, AF speed acceptable. Great for video since that's what it was meant for.
ZM 50 C-Sonnar - love the wide open look, but the 1.5 crop factor makes it harder to use as the default lens.
'Cron 50 DR - Sold this after I got the ZM Sonnar, but before that, it was my goto lens because I can get close focus without the hawk helicoid M adapter.
VC 35/1.2 - This is what I end up shooting with most of the time, in door, low light. Creamy bokeh and excellent sharpness.