Silver oxide batteries are available in two types. For Energizer batteries the better style is the 'H' series, examine
the discharge curves:
http://data.energizer.com/PDFs/357-303H.pdf
http://data.energizer.com/PDFs/357-303.pdf

Likewise the 'SR44' and 'SR44W' are preffered over the 'SR44SW'.

The distinction seems to be the electrolyte, KOH providing a flatter discharge than NaOH.