Hi there.
There are quite a number of different types of waders. If you can tell us what you will be using them for (just wading in to throw lines in, float tubing, river fly fishing etc.), then some guys can tell you what they use.
For float tubing I wear the neoprene ones (thick wetsuit type material), for 3 main reasons.
1) The risk of you getting water in and drowning yourself are slimmer as the wader comes up to your chest and then you have strong straps that go over both shoulders. They are also not as loose as the boot type waders.
2) Winter fishing - they are OH SO LEKKER WARM!!!! Wear a pair of those thermal pants from Due South and a T-shirt and jersey underneath, and you're sorted!
3) They have booties which are made out the same material as the suit - neoprene. I like this because I can wear the diving fins rather than those fit-over-gumboot type fins with a shoelace - those things are HORRIBLY uncomfortable to wade with, and because the fins are short and hard your ankles hurt. You kick your butt off , and you go very slowly.
I have a U tube which is harder to wade with than a V-boat, I weigh 105kg, and I wear neoprene waders with the diving fins. My buddy has the snowbee V-boat which is generally faster because of less drag in the water, he wears the snowbee gumboot type waders with those fit-over-boot fins, and weighs 75kg - I kick his butt all the time, by miles! Also, his legs tend to get extremely sore after a while because of the way you have to kick with those gumboot wader fins.
So from my personal experience, I would go with neoprene waders if you are float tubing. Only downside is in summer you're going to cook in that thing - but that is why I got myself the Sensation goretex type waders with the booties for summer - sorted!
You also don't have to worry about diseases and those dreaded leaches!
For fly fishing you can use 2 types.
1 is the Sensation one I mentioned above, Goretex with booties, and then you buy proper wading boots which have felt underneath (the felt is for grip, and the boots are stiff so you dont hurt your feet in the rocks).
2nd option is to get the standard snowbee waders, chop the front sole of the boot off (grind it smooth), and glue felt underneath yourself. Although this is a cheaper route to go, the underside of the boot is considerably softer and you could land up hurting yourself and getting your foot jammed between rocks, especially when you're fishing places like Yellowfish Paradise. If it is mainly for sandy areas, no problem!
Price indications:
Standard snowbee waders +- R350
Fins for above +- R250
Explorer Neoprene waders with booties +- R550
Sensation goretex waders with bootie - +-R 1000
Fins for above: I paid R99 at Game for the Divetek type, the ones with the adjustable buckle that goes around your heel.
Fly fishing felt type boots - R600 and upwards.
Thermal under pants (long ones) - R150 from Due South.
Hope this helps.