I just went through this selection process. Man, there are LOTS of opinions. Here's things to consider.
1. Dillon has a no nonsense, great warranty, but the extra waranty coverage is reflected in a little higher price.
2. The LNL and Dillon 650 are pretty comparable.
3. The LNL has a GREAT die switching system
4. The EZject on the LNL is way better than their old LNL system. It really works great.
5. Both the Dillon and the LNL will last many years, and with a little maintenance, your kids will give either to your grandkids.
6. Most people have the Dillon
7. Hornady also has a great warranty, and the times that I have used them (die parts and a lost press part), they replaced the pieces VERY fast, and didn't charge me a cent, even though it was my fault.
Bottom line, I bought the LNL, and haven't looked back. It is truly a fine press, and is made like a fine piece of machinery. The Dillon is great too.
Dillon 550 $420
Dillon 650 $550
LNL $395
The LNL is a better press than the 550, and has more features.