I have tried so many different types, and I cannot find anything I like more than the Dunlop Aciforts (non-steelie version). However, I am a little limited in what I can wear because I have a high instep which rules out quite a few brands particularly when wearing wetsocks.
I find the Aciforts have very nice flexibility, deep tread and are lined (I tried non-lined rubber wellies once which will probably last longer than me, but they are almost impossible to get on and off).
The Aciforts maybe haven't got the best longevity (a few years of regular caving, but significantly less if digging).
I wore steel toecap ones for a while, but the damn steel part kept jamming in between rocks, requiring welly removal to extract them, so they quickly got relegated to the garden.
I tend to have a few pairs of Aciforts on the go... some 'nice' untrashed ones with good tread which I save for horizontal trips (particularly slippery boulder hopping in Ease Gill or South Wales where grip is everything) and a few less-good pairs for digging or predominantly vertical trips.
But ultimately, the choice will be driven by what fits the nicest for you, this will vary from person to person