Some more information on my vote. The Omega is the main family machine, and is what we use for internet access. I typically use this machine every day, for a variety of productivity tasks including web design and spending too much time reading Usenet. It has Select 3i4 installed.
The A7000 is a RISC OS 3.6 machine, and is really only used by my parents for working on Impression Publisher files that won't convert well to Ovation Pro (our version of Publisher being so ancient it still has a dongle and won't work on the Omega). I sometimes use it for games that aren't happy with RISC OS 4 or Select.
I note you don't have an option for the A7000+, this is the "other RISC OS machine" I mentioned. This is my personal machine, and is something of a pet project of mine as it represents the RISC OS machine I may have got when I went to Uni had I realised that I didn't actually need a PC. It has a 128MB SIMM and RISC OS Select. I am considering fitting a CDRW drive in the near future.