Recommendation purely based on experience: Pjur! Pjur's Original formula and Analyse Me! formula are AMAZING... dimethicone-based, it's far more refined than silicones and they don't leave the oily-feel or residue. They're perfectly fine for vaginal intercourse with no problems with the residue backup in the urethra, it's nearly pH neutral, so it doesn't have any lingering effects like pH imbalance, yeast growth, or urinary tract irritation, either. Totally glycerine and paraben-free, hypoallergenic... I can't say enough good things about it!