It's been said once already, but with footwear, fit is your over-riding priority. All the shoes / boots being mentioned here have subtly different characteristics due to the different lasting used by different brands - the TNF shoes tend to have a bigger heel cup area than most, Brasher stuff ditto but also high volume elsewhere, Salomon is lower volume and the Elios seem snugger than some previous models etc.
Your best bet is to go to a good outdoor specialist without preconceptions and see what fits your feet best. If you're really concerned about grip on rock / rock-like surfaces, check out a scrambling-orientated-type shoe with sticky rubber - usually mid-way between rock boot rubber and boot rubber - though often these won't have particularly good grip on softer surfaces, look at the sole pattern and make an educated guess bearing in mind that the flatter and less defined the sole lugs, the less effective they are likely to be.
You can also guess a little from the feel of the rubber. If your thumbnail makes an indentation, the chances are that the sole is going to conform to the micro-contours of the rock and give you reasonable grip. If the rubber feels very hard, it's less likely to grip well on hard and wet surfaces.
It helps a little to know how low rebound climbing rubber works: based on aircraft tyres, it's soft enough to mould to the tiny flaws in the surface of whatever you stand on, increasing the surface area of rubber in contact and thus grip. It takes a little time to do this, which is why sometimes a hold you slide off initially will grip after you weight your foot for a second or two.
It's not quite that simply and sole design will also make a difference, but that's a reasonable deductive starting point. And also bear in mind that the softer the rubber, the faster it's likely to wear.