Brake cable upgrade options.

I upgraded the original brake and gear cables and outers on my basic Allez using a Jagwire race pro kit. It made a noticeable difference to the response of the gear shifts, a lot snappier. The braking felt more direct and easier to control the force. The two major differences between the original equipment and the jagwire kit was the "hardend" section of the brake outer that went under the bar tape which I think helped reduce friction in the tight curve on the bars and the cable end caps with seals which have kept the cables running smoothly through the last year of commuting. I've also replaced the blocks with swisstop green ones. These also improved the stopping force and controllability of the braking.

Have to agree about looking at your pads. The original pads with my TRP Spyre cable actuated brakes were very 'meh'. I replaced them with cheap semi-metallics from Discobrakes and they're now fantastic.

To try to summerise.

The cables themsleves don't seem to make a difference maybe a few grams here or there. Some are teflon coated for smoother running or longevity depending on who you believe.

Outers can make a differrence. Alligator, ilinks and Nokon are all of the same thought, little aluminiun beads through which a teflon liner is run. I like Nokon for tighter or fiddly cable runs. The majority of the rest are steel wound with a plastic outer.

Not sure if you'll get better stopping power as this is mainly a function of the lever-caliper pull ratio and/or pad and rim material. Some calipers also allow you to adjust feel, but I just gave up after hours of fiddling.

On question I always ask is can you lock you back wheel with reason force? If so then more power is pointless. If no look at playing around with brake pads.

Compressionless brake cable outer housing (not necessarily the cable itself) makes a big difference, especially to cable disc brakes. Jagwire KEB-SL is good (strands running lengthways along the housing, NOT spiralled around) but tricky to find in decent lengths. Packs with one front length and one back length are available though.

I have happily bought Jagwires in the past and would do so again.

Powercordz and suitable ilinks will get you the best performance possible from the cables, it will cost you though....

These are all just wires. I doubt very much you could really tell the feel between a new set of standard cables and these expensive versions

Re stopping power. Only one worthwhile option, upgrade to hydraulic, either rim or disc. The feel and modulation is far superior to cables. Lots of money