A first mechanical watch is less about the brand on the dial than about how well it fits the life you actually lead. Answer these questions honestly and the choice becomes much smaller.
Manual or automatic?
A manual-wind watch needs winding every day or two, and many owners come to enjoy the ritual. An automatic winds itself as you move. If you will wear it daily, automatic is easier; if you want to feel connected to the machine, try manual.
What size suits your wrist?
Ignore what looks good in photographs. Try watches on, and look at the distance between the lugs as much as the case diameter. A watch whose lugs overhang your wrist will never sit right.
How much water resistance do you need?
For daily life, 50 metres is plenty. If you swim with it, look for 100 metres and a screw-down crown.
What will servicing cost?
A mechanical watch needs servicing every five to ten years. Ask what that costs before you buy. It is part of the price of ownership.
Will you still like it in ten years?
Choose the watch you will reach for on an ordinary Tuesday. The rule worth ignoring is the one about buying only what will hold its value. Buy what you will wear.