I prefer wax but sealants are OK if they are applied properly. In my experience they never last as long as claimed - maybe 6-9 months but you can apply wax on top. You can't apply sealant on top of wax.
I don't bother with sealants because I enjoy washing my car and waxing it regularly. Sealants are for those who want protection from the elements without having to do a lot of work. There are negatives to sealants too.
1. Sealants will not give you the wet/shiny showroom car look that carnauba waxes will give.
2. Wax cannot be applied over sealants. It does not adhere well and will not last.
3. Sealants are expensive to apply since you will have your car thoroughly washed, clayed and polished before sealant is applied.