You can also ask Long Tail Pro to get extra information like “Global Search Volume” (amount of monthly searches globally for each exact-match search term), “Domain Availability” (to see if exact-match domains are available), “Google Title Competition” and “Bing Title Competition” (this is the “allintitle” search that checks the number of sites that are using the same keyword in the title of their pages).
This might be the easiest way to make Long Tail Pro pay for itself. I’m pretty sure that the affiliate program is open to anybody (even if you don’t currently own the product). Simply get signed up and then promote it any way you see fit (within the Terms of Service, of course). If you couldn’t tell, I’ve been doing this for quite awhile via this blog and I’ve earned a healthy sum of money over the years as a result.
So which tool should you use? The simple answer is ALL of them!! If the data from several tools suggests that a keyword may be a good keyword to target, than you should feel fairly confident that it is. If your results appear to be contradicting one another for a particular keyword, then you may want to be hesitant in including that keyword in your selection. SEO professionals should never rely on one resource for research. No one tool is going to be 100% accurate and you stand the best chance at making the correct strategic decisions by using a variety of sources.
The limit on manual keywords could be higher. I personally wish we could input 10,000 keywords at a time, instead of 200. However, I understand the costs that Long Tail Pro has to maintain each time a new manual keyword is input. Not a deal breaker, I just wish the limit was higher. (To be fair, I don't think most keyword tools have a bulk manual option at all).