I've used both... generally speaking... (as in generally)... sealants last about 2-3x longer than waxes but aesthetically, mas maganda ang depth ng carnauba... sealants will give you gloss like as if naka shrink-wrap yung kotse but no depth... carnauba gives you both depth and gloss... but doesn't last as long coz it melts/breaks down at faily low temp (mga 40something deg C ata)
There are limited sealants available here... AFAIK here are the ones that I see off the shelf: (don't ask me about price and where to get, if I didn't list them, I don't remember)
Turtle Wax Finish 2001 - Almost anywhere car waxes are sold
Simoniz Polymer Sealant - Almost anywhere car waxes are sold
Liquid Glass - Concorde
Autoglym - Infinity
Formula 2001
Of all the ones listed, I have tried Simoniz and Liquid Glass, the latter being the much better one... There are other brands out there (abroad) like Zaino system, Klasse, Meguiar's #20 (Kamias doesn't stock them) etc etc etc...