If I had it all to do over again. I would get all the presses in the same model and that would be a 1050. It saves time in changes and you only really have to have one set of spare parts.
I don't have a 900 but everything else, and use each one depending on how many copies I need made.
The square deal for rounds I don't use very often - .44 mag
550 for .38 special
650 for .40 S&W
1050 for 45 acp and another for .223
Once the press is set up and I have the load that works for me, I can just go to the shop and crank them out. I did not get these all at once but when I found what I thought was a good deal at the gun shows or on Ebay I bought it.
Once you get the primer machine from Dillion you will give up anything else.
Until I actually got into reloading, I thought it was time wasted. I should be shooting or training. But now I actually enjoy turing out a quality product and seeing how far I can push the envelope. I get a kick out of making bullets that you can't walk into the store and purchase. LM