Base your decison on how many rounds you want to load per week or per month. Typically, you can get 200 rounds an hour without too much drama (and up to 300 if you work at it.) out of the Lee Classic Turret setup with a Safety Prime system and a Pro Auto Disk Powder Measure. The Dillon is capable of 550 if you work at it, though most folks take their time and turn out around 350 an hour.
There's a significant cost different between the two, especially with caliber conversions. I own a Lee Classic Turret and a Hornady LnL progressive. I used to own a 550. Here's my take, based on reloading on all three:
1. If I were going to load a bunch of different calibers in fairly low volumes (50 of this, 200 of that), I'd get the Lee Classic Turret.
2. If I were going to load a lot of ammo, in the thousands of rounds per month, I'd go with the Hornady LnL, as it's about the same price (sans casefeeder) as the 550 and performs as well or better (particularly with rifle) than the 650.
A final thought. BEFORE you buy any progressive with it's significantly higher caliber conversion costs, make sure your round count justifies it. A buddy of mine has competed for years in IPSC and IDPA. He loaded most of those years with his Dillon 450, a press capable of 200 rounds per hour at best with it's manual primer loading and manual powder dispensing. (leastwise, that's what his had) In most cases, a single stage press like the Lee Classic cast single stage and a Lee Classic Turret press is an ideal set up for most shooters out there. If I had bought those two presses years ago, I probably would never bought another press and I shot IPSC and High Power back when on a really regular basis. That's how handy, affordable and versatile the Lee Classic Turret is.
Now if you're trying to crank out 2000 rounds a week of one caliber, you probably want to go progressive. In any case, both presses you list will do a good job of reloading.
Regards,
Dave