hmmm. Hard choice, I have alway liked both and had both, as they are more affordable than the newer M3s...but now I do have the E30M3 already. Here is my 02cents.....

With regards to the price (world market price/not Philippinemarket price) The 1st gen E36M3 is cheaaper than the E30M3 assuming they are in similar condition...
Performance: The E36m3 beats the E30m3 with regards to power
Pogi points : The E30 m3 wins with the wide flares and racing look
Value : The E30m3 still wins hand down....the prices are actually increasing every year as it is getting harder to find one and more BMW enthusiast are wanting one to have and keep!
Reliability : E36m3 is better, its newer, more advanced technolgy

If you just want to drive around town in an ///M car, then get the E36m3!!!
But if you have budget (a lot) and time...get an e30m3, put the necessary upgrades for suspension and engine....you will have gokart like handling and 4cyl ///M that will hang on to the 6cyl ///m cars with out a problem..