My favourite Amiga is certainly the A1200. A cheap low-level "newbie" computer that grows the same way your requirements grow. Need more memory? An internal HD?, a faster CPU? a NIC? -> no problem.
And that's exactly the reason why tower conversion kits for A1200 computers made sense: I bought a tower and a Zorro2 backplane six or seven years ago. *Much* cheaper than upgrading to an A4000.
I still have my first A1200, purchased nearly 10 years ago. I couldn't afford an A4000 back then, but my A1200 is now more powerful than most A4000s out there.