Its a confusing world out there. Which power meter suits you best. Lets find out:

Wheel Hub system

Pros – ANT + low cost, easily installed , and can can easily be swapped from bike to bike.
Cons – Limits your options in races as if you want to run a set of race wheels then you race without power,

Suitable as a budget option gets you on power for reasonably low cost and allows you easily swap between bikes, also suited to MTB riders who want power on their road bike but race on their MTB. Hence no requirement for road race wheels.

Crank Based system

Pros – ANT + allows use of any wheelset, can be swapped between bikes with the same Bottom bracket, power measured at the crank can be more accurate. Can be more durable
Cons – can be more expensive, whilst you can swap them between bikes it maybe beyond the average cyclist. You may need to find a specific crank system to match your bike. Generally needs a bike shop to install.

Pedal Based system

Pros – ANT + allows use of any wheel set, can be swapped between bikes, mid range in cost, can be used on MTB, easy to install and set up,
Cons – Its new to the market so durability is unknown at this point,

Crank Arm only

Pros – ANT + low cost , easy to swap between bikes
Cons – must have same cranks and crank length on both bikes, new to market unknown durability