IMO chromed brass is the most durable for taps and accessories. Most stainless is Chinese import and is liable to dark specks and rust stains due to poor quality.
If you browse the mass-market outlets like Wickes, screwfix, B&Q and Toolstation, you may find that certain lines are on sale in several of them, under different names. If you can find a style you like, you will find differences in price, especially at the first outlet to put them on clearance, and some excess or clearance stock will appear on ebay.
You may find that a "set" of accessories works out better value than buying them individually, and you can buy extras to match.
Ranges change every six months or so, so get a few extra shelves, gown hooks and towel rings that you might be unable to match later. Glass or ceramic items like soap dishes will get broken.
I like to have two toilet roll holders on the wall so you don't need to put the spare roll on a shelf or windowsill. You can have one for left-handers and one for right.
I'd say get stuff that is attached with screws, not glue or suckers. It is much less likely to fall off.
I recently discovered that the towel rails in my chosen rails look almost the same as chromed grab-rails, so I've used grab-rails by the bath, shower and WCs that can be used for towels and things, but are very strong and may be useful if some slips over or becomes unsteady.
You may find that you can get wall lights, door handles and cupboard knobs that match the bathroom accessories, which is a nice touch. Maybe even light-pulls. Certainly try not to mix brass/chrome/brushed stainless in the same small room.
Please don't put a shelf or cabinet over the basin. When a glass bottle or jar falls out (it will) the basin will be cracked.