Personal opinion: Robertson is hard to decipher. He uses a lot of jargon that he does not clearly describe. Smyth is easier to read, so if you want to understand older terminology, using Smyth's explanations and Robertson's examples works for me.
If you don't care about learning older terminology, a more modern grammar is easier to work with. Again, though, Robertson's examples are worth their weight in gold.
ἐξίσταντο δὲ πάντες καὶ διηποροῦντο, ἄλλος πρὸς ἄλλον λέγοντες, τί θέλει τοῦτο εἶναι;