EFI is awesome.
Carbs aren't bad either.
With either one, let the fuel get old and it WILL have problems. EFI is under a lot more pressure and will usually run on old fuel. For a while. Until the injectors become plugged.
I know nothing of any outboards other than the Yamaha's. The F15 and F20 are the same exact outboard. Carb is different. And so is the price.
The F250, however, is way different. Bigger engine, bigger carb, bigger leg, etc. I've run a 1548 War Eagle with both an F20 and a F25. The difference is huge. The F20 was slow to plane and ran 19-20 mph. Bare boat with just me in it. The F25 jumped right up, ran smoother at top speed and maxed out at 28 mph. It would run 26 with 2 people and a big ol dumb black lab. The F25 is around 170 lbs. Heavy it is. It needs power tilt and it can be had for a little extra cash. The F20 is light (around 125 lbs, IIRC) and easy to tilt. Just not nearly as powerful as the F25 is.
SO in the case of Yamaha's small motors, I would definitely say the 5 HP difference certainly is worth the extra weight. The new F25's have tilt assist which is nice once you get used to it. You can tilt it with one finger. I've run some F40 tillers with tilt assist and it's pretty cool. Almost better than power tilt; IMO, but power tilt is usesless to me without trim.