Any opinions on what the best e-collar for retriever training would be?

I am a fan of tri tronics err garmin - sport pro model. I have had tritronics collars for 20 yrs. 1st collar lasted 17 yrs, just got the sport pro 2 yrs ago. They used to be built in US, not sure now.

Friends use sport dog as well

i like the sport pro better as you can use tone and vibrate w/o switching from E stim. Its nice to give fido a warning by tone or vibrate before going to lectricity. Also on the collar the tri tronics has LED lights to show when collar is being used and battery level etc.

Sport dog will work just my 2 cents

If you use one of the garmin collars, make sure the prongs are long enough. I found that the prongs that came on the collar were short compared to other collars even for a lab. Other than that complaint, I've found that garmin makes a good e-collar.

Garmin sport pro.

LED light, manual control, and bark limiter feature all in one. I've had mine for 5 years with no complaints.

I've got a Dogtra 200 Gold NCP that's 21 years old and still working great. I can't testify if newer models are just as good.

I only had to replace batteries every 5-6 years or so, maybe longer.

Lion county supply is a good vendor too

For a lab use the long prongs.

Also remember when the dog is wet they are more conductive so turn the setting lower one or 2 levels or it will be too much. You just want the dog to notice the stimulation not yelp or be in pain. Good luck.