Some offers may have low commission or conversion rates: Not all affiliate offers were created equal. Some offers pay out more % per sale. Somer offers just don’t convert that well despite sending tons of traffic to them. It is important to pick a good offer that converts well & pays out high. Look for offers that are the most popular in your niche at clickbank.com, or look at other affiliates ranked on page 1 of Google within the niche and look at what type of offers they are promoting. Most likely those are the great offers to promote in the niche.
In the long-term, it affects your versatility, functionality, and, of course, your brand. In the short term, it can certainly add/take away a lot of headaches. That said, just like choosing a physical house or office, there is no such thing as an absolute “best” or “top” choice. There’s only the right choice relative to your goals, experience, and circumstances.