Here's one not mentioned yet?
My actually most used PI is an older 7A12. Its illuminated push button vert sensitivity selection for both 105MHz channels
rather than a rotary switch I find quicker and more natural to use.
But for general purpose fault finding or development work the variable DC offset on each channel is very convenient
when you are looking at a low level dc coupled signal raised up on a higher circuit dc offset, which is often the case.
Was unsure of buying it at the time because of its age , but It has become the most used plug in I own!
Its only problem has been the loss of the pull out which fell out and was then lost, so its become
a permanent part of one of my 7603's for years now and will stay there!