It depends on what you want. Merkur razors have a better reputation, but they also cost more and they don't make a TTO. Parker makes several TTO DE razors that are fairly affordable, and are considered superior to Chinese razors ( the only other source of modern TTO razors). So, if you want a TTO razor that offers good quality for the cost, then Parker makes several good choices. If, OTOH you want a razor with a reputation for a bit higher quality, don't care if it is TTO, and don't mind spending a bit more money, then Merkur is probably a better choice. Also, if you'd prefer a Merkur, but price worries you, they make 3 piece razors, which cost a bit less than their 2 piece models.

It is ultimately your choice. They are both reasonable options that you will probably be quite happy with.