I am a VERY regular user of track and train electronic collars . Gil has perfectly described the differences and features of the current Garmin line. I have had personal experience with most , if not, all of the competing brands. I too have settled on the current Garmin offerings.
I moved out of the aging Alpha series of collars and their older TT 10 and TT 15 products to the newer platforms at the beginning of this season. I think I am using the best product on the market.
I will drop one little piece of advice based on my personal experience. I have for years bought my dog electronics from Gun Dog Supply , in MS. and in particular dealt personally with owner Steve Snell.
He is absolutely great to deal with.
First off, he is a BIRD DOG guy for real. He frequently hunts near by on various leases he shares on the South Plains. Great companion in the field and he shoots a nice small bore SxS at quail.
I called about upgrading and he spent most of an hour going over the features of the 200 and 300 series as well as the uses and applications for the "i" features. Based on my hunting habits these days we settled on a 200 unit and the related T25 collars. The Best system I have used yet.
Just another mention here is the GREAT customer service and follow up after the sale. A software glitch in one of my hand held units put my hunting on hold one morning. A call to Steve for help, he took the time to walk me thru a diagnosis of the problem, prescribed the needed software update, and coached me thru the process of plugging into my PC and downloading the needed fix. Back in the field with that unit after lunch.
Real Customer service of the old school. I highly recommend him and his fine company.