I'm an old newbie also - although I have been a newbie for about 4 months now.
There is a considerable difference between brands and it's not as straight forward as looking at specs either. For example, I bought a brand new SCX NASCAR Camry. It has floating chassis and a sprung guide as well as brass bearings and double copper braids. Should be much better than an old Scalextric Taurus from 1990. It's not - it's a piece of poop and will need considerable attention to tyres, lubrication etc. to even get close to the Taurus which I bough on Evilbay well bashed and haven't even had the top off it yet!!!
I have a Ninco Subaru WRX with band driven 4wd and it FLIES round my digital track about 1/3 faster than a brand new Scalextric F430 (which is itself quite a quick car). The Ninco looks really basic and nothing much different to the Scalextric chassis but it goes like stink. An old SCX 4wd Subaru that I bought for its direct drive 4wd is a bag of bolts by comparison - its motor is noisy, the transmission is noisy and it grinds its way round the track.
It depends on your style of track (different cars handle differently within brands as well as across brands), your need for aesthetic appeal vs. your need for speed and so on.
If you are going to join a club and compete then go to the club and see what others are competing with - it's down to specific models as far as I can tell not just brand.
Looking at the forum it seems that clubs run lots of different classes so I guess you could see what your prospective club runs and choose a class or two that you like the look of and have a go.
If you are simply racing at home I would say it's more important to have evenly matched cars than the fastest brand. I own Scalextric, Slot.It, Team Slot, Ninco, SCX, Fly and AutoArt cars. They are all capable of being driven out of the slot on every corner. At the end of the day it's your shout what you buy - buy to please yourself not anybody else!