I have one each Dillon 550 & 650 and three 1050's. As others have said, you can make a lot of ammo on a 550 but overall I like the XL650's (now the XL750) best for multi caliber work. Relative to the 550, the 650/750 have an extra location on the stage, are easy to convert calibers (especially if you tool heads you keep set up with a dedicated powder measure for each), very reliable and can be fitted with a number of mods such as a primer pocket swage that automatically fixed crimped cases. I've also run the RCBS Pro 2000 but not a Hornady LNL. The RCBS ended up being a gateway loader that just sits there today. Amongst the batch and if the budget allows, I'd recommend the new XL750. Don't forget to be ready to invest in a faster way to fill primer tubes - progressive presses eat up a hundred primers pretty quickly! Disclosure - After using Dillon's for several years for personal use, I'm now a Dillon dealer and therefore could be a bit prejudice. And, I'm also a Lyman dealer - I've added a Mark 7 to my 650 . ooooohhhh boy!