In deciding which hone to choose the first question is what type of honing are you seeking to perform, but budget and personal preference will also play a part.
Honing stones are either synthetic, such as the Naniwa stones we stock, or natural such as the Belgian Blue Stones and Coticules. Personal preference is key here. While there are many fans of the natural stones, I would say that the synthetic stones tend to produce a more consistent result and may therefore be a better choice for a beginner.
Honing stones are graded according to grit size, where the larger the number, the finer the grit. We stock stones from 1k (1,000) through to 12k (12,000).
If your razor has just gone beyond the ability of the strop to sharpen it, so you are just “touching up” the edge, you really need a 10k or 12k stone. In this category we have synthetic Naniwa Specialty Stones (in 10k and 12k) and also the excellent Chosera stones (10k) while in natural stones we have Coticule stones and a Chinese 12k stone. The Coticules and Belgian Blue Stones do not have a grading as such but should probably be considered about 10k in the case of the Coticule and perhaps 5-8k for the Belgian Blue. Much depends on the pressure applied though. In the right hands a Belgian Blue stone can produce a fine edge. For a first stone I think it safest to go with a Naniwa, probably a 10k.
If the honing work you are doing is more restorative in nature then there are Naniwa stones down to 1k grit, or perhaps a Belgian Blue Stone and Coticule combination.
For more information about the honing stones, I make some specific comments about the various hones we stock.