Shimano chains have always been reliable and long-lasting value-for-money, which is why so many riders continue to use them. Even though any 9-speed-specific chain can be used with the Tiagra kit (and it's okay to use others), there's very little incentive to move away from the dependability of the Shimano issue.
As long as they are regularly cleaned and re-lubed Shimano expect you to enjoy continually impressive performance from their chains. The Shimano Super Narrow ECNHG53C116I Hyperglide (HG) Chain is supplied with a joining pin partly fitted along with an additional spare pin.
Shimano also advise that while it was previously possible to re-join the chain without using a new pin each time, it is now their recommendation that you use a new pin every time.