I've had both the padded "sleeve" type of shinguard and the solid types with straps.

I really like http://www.amazon.com/RDX-Instep-Protective-Training-Kickboxing/dp/B009TP5NP4/ref=pd_sim_200_2?ie=UTF8&dpID=51mxZwjF0rL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=1AT8A7C7GS4S42MG2T0T they are good value and great protection.

Again the Thai brands like Top King and Twins have the best shinguards but may be too expensive if your only starting off.