Hi,
Welcome! Get that stuff out of its boxes!!
Of your Amiga stuff, the A1200 is probably the most expandable for the least amount of cash... Keep an eye on eBay for a 68030-based accelerator with 16Mb+ of RAM and it'll make a massive difference to the A1200's speed.
If you really have £££ to burn, go for a 68060-based accelerator, but you'll be looking at around £200 used for one of these...
Finally, if money is really no object, expand the A2000, get a fast accelerator, graphics card and Ethernet network card and you'll have a very usable machine!
- Ali