NGC 3918 in Centaurus is cool as. Perfectly round blue orb and it magnifies really well.
I havent observed many Planetaries but from the ones I have - the Ghost of Jupiter and the Spiral Planetary in an 8", the Dumbell and the Ring are my favourites.
Next up on my hit list is NGC 1360, NGC1535, and the one in M42.
[quote=AJames;252047]
John B (ausatronomer),
Yes, you are quite right in mentioning NGC 246 in Cetus, and it is indeed among the true "bread-and-butter" planetaries in the sky. 
This is a lovely object, especially for its fair size and its very pale blue colouration. It is probably just visible in 10.5cm, [ /quote]using my 11.4cm scope I was able to *just* see it from my light polluted backyard (LM ~ 4.5-5)