In Metro Manila and other Urban places I know where 3G is present, I always set it to WCDMA only... there is less possibility of a slowdown and to avoid a possibility of a handover to a slower data implementation specially in high congestion data areas.
On your Phone Settings>Wireless and Network....Network Mode using this two settings (GSM/WCDMA or WCDMA Only) depends on the current or what you are using for Mobile signal usage.
If you want to access Mobile Data Connection for faster mobile internet connection and you want a steady 3G signal of H/H+... you should set your Network Mode on WCDMA Only... if HSDPA/HSPAP is weak on your location you will really experience a fast battery drain since the Phone modem is boosting the amplifier to acquire 3G signal. Plus turning ON the Mobile Data really takes a lot of mAh from the battery compare to 2G connection Only.
If you are not using Mobile Data Connection for your regular call and text. Better set your Network Mode to GSM Only so that the Phone Modem will not constantly search for GSM or WCDMA Network. This can save battery power also since 2G signal acquisition doesnt need much amplification to acquire.