There are several new options in the power meter market with the announcement of the Garmin Rally RS and RK (road), and Rally XC (off road) power meter pedals.  Both versions feature two models; the 200 series for dual sided power measurement, and the 100 series has just one power meter pedal and one regular or "dummy" pedal.  What is refreshingly new is that the RS series is Shimano SPD-SL compatible and the XC Shimano SPD, whereas the RK series is Look compatible.  This effectively removes the hassle and barrier of changing your current pedal/cleat setup to a new and unfamiliar one.  The RK/RS100 single sided come in at a price point of $649.99, whereas the dual sided 200 are $1099.99.  The XC off road version is $699 for single sided and and $1199.99 for the XC200 dual sided.

Besides increasing choices to make them all but universally compatible with your current cleats, Garmin cleverly will be introducing upgrade or conversion kits that allow you to swap your power meter from bike to bike.  Essentially a pedal without the power meter.  This is a much more economical solution compared to purchasing multiple complete power meters in the form of crank arms, cranksets, or spiders.  You may also convert your spin bike into a fully interactive smart bike.  

The main challenge of choosing a power meter is compatibility; generally with your crankset.  The variety of power meters on the market today require selection of the correct model, crank length, gearing, bottom bracket, etc., to match your current crankset, or start over which is expensive and has its' own set of challenges.  The shortage of bicycle parts has caused many of the models to be out of stock indefinitely greatly limiting options.  Pedals on the other hand are much more universal and with the introduction of these models Garmin casts a very large net over virtually the entire market.