id say hardwall if you aint got a mixer cos its nice and light, mix in a bath, but you need to be bloody quick...
if you got a kenwood i use sand and cement, waterproofer/plastisiser 3:1 maybe 4:1, bit more work, need 1/2 ton of sand 8 bags opc and a groundsheet.
get the labourer to mix it, take it straight out the barrow, got ages to float it up and it sets like bloody concrete...
well it is, basically

matter of preference, its what you get used to i suppose, render can be a bugger if the bricks wont suck, you need to get it on, rule it off and stay off it till u ready to float, dont play with it or you just drag the water to the front and it falls off again...you want the bricks to suck the water in, it dries from the back..
depends on the bricks too, anything hard youre prolly better of with hardwall. Old and softish, like commons should be fine, you need to give em a good brush first too...
if you aint too confident id stick with hardwall...