Emax is seriously messing up the whole FPV motor market with their Eco II line. As far as I can tell, they are making a $22 motor and selling it for $12 just because they want to be taken seriously as a motor manufacturer. I have no idea what the actual motivation is, but the Eco II is a seriously great value. It even has premium EZO bearings (an area where other budget motors often skimp).
At the time of this writing, the Eco II comes in only three sizes: 2306 and 2207 ideal for 5″ or maybe 6″ props), and 2807 (ideal for 7″ props). For 5″ props, choose 1700kv for longer flight time on 6S batteries, 1900 kv for more power on 6S batteries, or 2400 kv for 4S batteries. For the 2807, choose 1300 kv for long range cruising on 6S batteries, 1500 kv for a bit more power on 6S, and 1700 kv for 4S, or for 6S builds intended for aggressive freestyle.
If the Eco II is available in a size that you want, from a store that you want, it’s hard to argue that you should buy anything else. Nearly everything else in this price range is inferior. And motors that cost twice as much may be better, but are they twice as good? Especially if you’re just going to destroy them in a crash.