Q: which imac to buy

I have an older imac approx 8 years old . i am considering getting a new one .It came with leopard and i upgraded to snow leopard but that is as far as I can go to upgrade . I need some advice .

I want another 21.5 imac

i want 16 GB memory

1 TB hard drive 

I would like the trackpad since I have a wireless mouse

I want the wireless keyboard

My question is which processor should I buy

also which Hard drive the ata drive or the fusion drive and which processor

I am a senior who surfs the web does email and social networks . I do play  a few games . I have a fair amount of music on my mac and I use i photo alot

any suggestions would be appreciated

My biggest hate is getting that coloured beach ball every time i try to do anything on my current imac