Hi David,
Welcome to IceInSpace
Have you read this two part article: General Principles for Choosing your first Telescope
http://www.iceinspace.com.au/63-260-0-0-1-0.html
Its a few years old now, but still a good place to start.
Where are you located?
The best advice is to get you along to a (preferably free) observing session, where you can look through various equipment, and talk to owners who have travelled the path you are starting upon.
In reference to the smaller 4 scopes listed:
To steal a quote from part 2 of the article, be careful you do not finish up with a telescope that can automatically pinpoint countless objects that are far too dim for it to see.
And...
Any object within the grasp ... is either visible to the naked eye or fairly findable with a decent star atlas.
Having been down this road myself, my experience is that (they are all good scopes but) you will soon run out of things to see with these scopes, and be running for the larger aperture DOB before too long.
My recommendation, to save some time and cash, look at buying a DOB up front, 8" is good, 10" is better, 12" is starting to get a bit awkward to move about. And you can get it with GoTo up front too.
Personal preference: I would recommend Skywatcher goto DOB or an Orion.
This one looks to be excellent value
http://www.bintel.com.au/Telescopes/...oductview.aspx
But the Bintel (GSO rebadged) and Meade are also highly regarded by many on this site.
Good Luck with your purchase