The press you buy will be partially dependant on the volume of ammo you need, and on the contents of your bank account
If you shoot a lot, you'll need a high volume press like the Dillon 650. If you only need a 3 or 400 a month, then the Dillon 550 or a Dillon SDB or the Lee Pro 1000 (though not as well built as the Dillon, and the warranety isn't nearly as good) will handle it. If you're only gonna shoot 1-200 a month, and have plenty of time, you can use a single stage press like the RCBS Rockchucker.
I'm a big fan of Dillon. While I don't shoot nearly the volume I used to (I'm down to about 1500 a month), I still don't want to spend much time loading. So my Dillon 650 is a great solution. I can load up the ammo I need for the month in about 2 hours. Quick and easy!
So, it depends on what you want to spend and how much ammo you need.
For shotshells, unless you're shooting every weekend (and even then), it may not make sense to roll your own. It still ends up running $2.50 to $3 to load up a box of shells. Factor in around $100 for a press and the payback takes quite a while.
Doc