The best way to discover what works best for you is to experiment with different waxes and additives until you come up with a formula that looks how you want it to look, smells good and burns good. Containers would seem to be the easiest type of candle to pour. The biggest complaint made about containers is wet spots. If it's any consolation, the manufacturers are working on it. They are supposedly getting close to an improved poly wax that doesn't shrink.
Some candlemakers prefer to use a mixture that shrinks completely away from the glass.
However, this can create a problem if the candles are shipped. Any warmth will cause the wax to melt to the glass, causing spots. Also, having the wax attached to the glass produces a more vivid color with no refraction. Two things appear to happen to cause the spots. Shrinkage and trapped bubbles.