I've got both the Dillon Square Deal B, and a XL 650. Both machines are great progressive loading machines. Dillons are built to last a lifetime, and have the warranty to back it up. But, they do require some minor tweaking, as with any other machine, from time to time.
I've been churning out pistol/revolver rounds with the SDB for over 20 years. I have no complaints with the quality, production rate, or customer service from Dillon. My XL 650 is fairly new, and works like a fine Swiss timepiece.
I also have a few friends whom own the Lee Pro 1000 machines. Although not the quality of the Dillon, they do work, especially if you take your time, learn the machine, and fine tune it. If you plan to un-box it and begin producing 300 rounds per hour, you're going to be disappointed. But, the machine is certainly capable of 300 rounds per hour, if you take my advice above.
Several here have mentioned the Dillon 550B. I personally like the auto-indexing feature on some machines. The 550B is not auto-indexing, so I didn't even consider going that route. I did try a Hornady Lock-N-Load AP, and did not have success with it. The priming system is it Achilles’ heel.
Here is a link to a good YouTube Video, where the guy goes over the pros/cons of the Lee Pro 1000.
Would I purchase a Lee Pro 1000? If I had X number of dollars to spend, and the Lee Pro 1000 fit inside that limit, yes I would.
Hope this helps... Take care.