There is no single media that can capture the rhizospheric diversity. I suggest that you attempt different selective media in half and quarter strengths to isolate specific groups of microbes. By this you may capture the oligophiles that normally do not appear on rich media
To my experience I would suggest to use pour plate method (dilution 4-5) using R2A agar, Soil Extract agar, Nutrient agar & King's B agar...So that you will get diverse group of bacterial populations........for actinomycetes (dilution 3-4) ISP medium, Kenknight agar....for fungi (dilution 2-3) PDA, MEA & TSM (for Trichoderma)