I’d stick with Amazon if I were you. All of my Amazon sites only have Amazon affiliate links. If you use Google Adsense display ads on your site, you’re literally taking people away from your site for the sake of just a few cents with these type of ads. If you direct them just to Amazon, then you have a greater chance of earning more money from that click.
Amazon customers are loyal. Beyond that, Amazon customers--especially Amazon Prime members--are more than happy to convert. According to a 2015 report, Prime members are said to convert at a rate 22 times greater than customers that shop with other top online retailers. So, if you can tap into that audience and appeal to their willingness to spend money with Amazon, you should see a good return on your decision to join the program.
Earning income via Target affiliates, however, requires a bit of work. Cookies expire in just seven days, and commissions can be as low as just one percent, so you’ll need to be operating a high-traffic website in order to make serious cash with this program. But with Target’s much-beloved brand reputation and vast catalog, relevant product links can be a big earner for established influencers.