Looks like the 1200's and the big boxes (3000, 4000) are the most heavily represented in the poll.
It does make a lot of sense... The big box Amiga's are the most expandable machines and then the A1200 is a very easily expandable machine and takes some really cheap upgrades like pcmcia network cards or compact flash readers and has built in ide and AGA.
A500 is more expensive to upgrade and you have less options, even harder and less the A600 and expensive. And the CD32 and CDTV, expansions are very rare.
The PPC systems like the SAM, Pegasus, A-ONE etc. seem popular options too although to be fair i don't really consider them to be Amiga's.