Canon 430EX vs Nissin Di622

I would not go for Nissin Di622 Mark I. Di622 Mark II is a good flash, however. Here is in-depth comparision:

Nissin Di622 Mark II vs. Canon 430EX II

The important 2 things to remember is that as a wireless slave Nissin is limited to group A Channel 1 and it don NOT have a HSS. That being said, Di622 II is very easy to use and it is reliable. It has optical slave modes, which Canon does not have. Some people also appreciate mini-phone sync port.

Between Canon 430EX II and I, Mark II wins with 20% faster recycling, support of in-camera flash controls, and silent operation 9 (no whining). Mark I, however, has a dedicate wireless slave switch, which some people go nuts for.

hope this helps you a bit. the choice is not easy and depends on you needs and plans for the future.