if by judging the filter alone, i cant see any difference between ufo type and mushroom type of filter... both also open-port filter that doesnt uses oem airbox...
IMO, mushroom filter with extended RAM is better in terms of cold air induction... u can direct the piping away from heat source, while ufo type cannot because it sits directly on top of the carburettor...
in terms of $$, of coz ufo type will cost less because we dont need RAM and adaptor to fit the filter.... but remember, if u intend to use back the same filter after u convert to efi engine, u still can use back ur mushroom filter... ufo shape filter cannot be used in efi engines....
well, at the end of the day after ur mods, this depends on ur driving style and how u custom build ur cold air induction to feed cooler air to ur filter.... my ufo K&N filter has 2 CAI hose facing it... not good enough for low speeds... but at higher speeds, both CAI hose able to feed sufficient cool air to my filter....