dunno where i saw it (somewhere here on xda prolly N1 forum) but some guys put every aftermarket battery for MANY phones up against HTC's stock batteries the astounding results:
NO aftermarket battery from ANY mfg. has EVER beaten HTC's stock battery...
(this is referring to batteries that fit in stock battery enclosure)
ROM: Iced Glacier
HTC Nexus 1:
T-mobile G1 Black x2 +1 white (warrantied out waaaay to many times)
*used for PSFreedom/XBMC remotes*