My Promariner Prosport 8, purchased in March, 2019, just crapped out. The wareanty was one year.  The Basspro chargers only have a 2 year warranty.  What’s the longest lasting onboard charger? I hate changing them every 2 years!

Well, it dang sure ain't something made by  Promariner.  I was a die hard ProMariner user for many years, before they went to China.  I bought one of the Chinese built ProTourny 300's, it didn't last and got another under warranty.   That one lasted about one month past the warranty, so I sent it in for repair.  They said it was too old and they no longer had boards for it (seems like it was about two or three years) but they would sell me a replacement at a reduced rate, so I did that.   That one also lasted just a couple months past the warranty, so I sent it back for repair.  Same BS, it was too old and they no longer had boards for it, but they would sell me a new one at a reduced rate.  I told them they could just take that one and stick it where the sun don't shine, I'd had enough of their junk.

Great charger while they are working, but I can't afford to buy a new one every couple of years.

I bought a boat that had a Dual Pro in it, and when I sold that boat, it still had the Dual Pro in at and it was about 12 years old. 

I have a Minnkota Digital MK330 I've had for several years that I just mounted in my Pontoon and it's still working.  I'm not a big fan of the way it works, but it works.

  

Dual Pro or Minn Kota. I'm pretty sure the BPS chargers are rebranded Pro Mariners 

3 years old in 18 days and has charged 3 batteries 2 - 3 times a week with zero problems.

Minn Kota by far

I put a ProMariner 3 bank in my boat when I bought it 16 years ago.  It's still charging just fine.