Hello again! "Tech-challenged" sounds better than "inept." 😉
Current iMacs come in two basic models. The lower-cost model has two USB ports for expansion; the other model has four ports Even for simple things like connecting a printer or backup drive, two ports can be limiting. Two ports could end up with your having to manage hubs for expansion, and that adds complexity I doubt you seek.
Is your current iMac's network connection wired or wireless?
RAM v. Storage:
We bought Mrs AJ a new 4-port M4 iMac last year to replace her geriatric 2011 21.5-inch iMac. Wife's uses of her shiny new iMac are similar to yours — on-line banking; email; some MS Word and less Excel. She checks product reviews using Safari. As you say, basic.
My opinions on storage v. RAM are based on our family's experiences plus posts from these forums:
— We see few users complaining here about "running out of RAM."
— We see hundreds or more complaints about "running out of storage."
Many of those people reporting are "basic users". As neither RAM or storage can by upgraded after the computer starts down the assembly line, it behooves us to buy today what we may need in 2-3 years.
Do not get any Mac with a 256GB drive. Those are the ones most commonly running out of storage space. Nothing less than 500/512GB storage seems appropriate for today's OS versions. If costs forces an "either/or" showdown between more RAM or more storage, the many sad "filled my storage" stories here have me voting to up-order storage.
For Mrs AJ's new iMac we upped the size of the storage but left the RAM at its current base amount of 16GB. Runs great for her needs and never shows as starved for RAM.
iMac v. Mini? Tough call. The Mini was touted in 2005 as the Mac for Switchers who already had a monitor, keyboard, and mouse. I read the Mini forums here and see quite a few questions about buying and setting up the required external monitor. The iMac does not require that added scoop of set-up complexity. Ours was up and running in no time.
We'll help any way we can, except for making your decision. Cheers! 🍺
Allan