At the simple level of SEO that we are discussing here, the thought process should be simple. There is one rule: Do what is best for your users. If you read Google's recommendations for SEO, that is what they tell you. Don't think about how your changes will affect the search engine, think about whether they are better for the user.
So in this case, the second one is much better. I would much rather type the second one into an address bar than the first. I might even be able to remember the second one, if I visited frequently.
If you are going to change your urls, I would also recommend losing the .html file extension and serving the page dynamically. so it is just toys/lego-star-wars Such a url can transition easily whenever you make technical changes to your framework.
Finally, you want to be super careful about changing any URLs. I would minimize the number of changes you make (it will always set you back) and make sure you have 301s from the old to new.
Speaking of tracking, testing, and measuring, keep in mind that traffic--not rankings are your end goal. I would use the ranking stats provided by google wmt as a rough indicator, but focus much much much much more closely on your traffic.