I like anything that has "atmosphere" - that invokes emotion. An image can be technically poor but if it provokes feeling then it is good art. I suppose I'm biased towards sci-fi and if I had to choose a genre then this is what I'd choose, though I do like landscapes also. In fact, I'm considering concentrating solely on sci-fi from now on, because although variety is a good thing generally, it doesn't help at all if you're wanting to get work. Then, it's specialisation that counts.