First came the Varix- I, II, and III. They were upgraded years ago to the VX-I, II, and III. Another upgrade was made and the roman numerals were changed to arabic numbers. VX-1, 2, and 3. Since then there have been several more upgrades, but the numbering system has not changed
Since 2011 the VX-1 has had click adjustments. The VX-2 is better than the VX-II, but there have been several upgrades since coming out with the VX-2's as well. The older VX-1's were essentially a Rifleman, but no longer. The Rifleman series is unchanged. The current Redfield is essentially an older VX-1, but current VX-1's are a much better scope for about the same money.
Starting in 2011 they upgraded their entire lineup again. The VX-3's were made better. The new VX-2's are using the same coatings and technology that were on the previous generation of VX-3's, but selling at the old VX-2 prices. This is the value point for me. I own a 2012 made VX-2 that is a better scope in every way than a 2005 made VX-3 I also own. I cannot see spending the extra $100-$150 for the VX-3 over the VX-2. The difference is so much better I ended up selling all of my roman numeral labeled Leupolds.
The current VX-1's are essentially a pre 2011 VX-2, but selling for around $200 instead of $300. I have the same 1-4X20 VX-1 on an AR. You won't be dissappointed. It is a far better scope than the older VX-I, II or III models