Many investors probably think of Fitbit (NYSE: FIT) as the most straightforward way to invest in the growing wearables market. However, shares of Fitbit have fallen more than 70% over the past 12 months due to concerns about slowing sales, declining margins, and rising competitors. Yet during that same period, Garmin (NASDAQ: GRMN) -- the unloved GPS and wearables maker, which has been losing relevance to smartphones and fitness trackers -- rallied 26% to a 52-week high.