are you sure what you state, hope you have true point to support what you said . look at nextag, squidoo,amazon...subdomain is cannot , but subpage is legal
1st one is a sub domain so its not a good option, coz google will treat as an entirely new site. Unless you want to do SEO + whole content for the whole thing fresh, 1st options isnt so good. 2nd and 3rd options are the same though I would go for the 2nd one.
cordlessdrill . com/makita-cordless-drill The words are more catchy in googles eyes. When someone googles a question, and the more the keywords match your website link, that will help you alot.
cordlessdrill . com/makita-cordless-drill would be what I'd use. Why? Because you have more of your keywords in the domain name. If you don't add cordless-drill then you've missed out.
Keywords in url helps in ranking but it is not a mandatory thing. You can have related keywords and just concentrate on your off-page optimization by building a good back link and also have good content. Many high PR websites doesn't have any keywords in url but only the content and the link building matters.
I think you should go the first one as it contains the your targeted keywords in the main domian rather in internal pages.
IF Your Keyword is "makita cordless drill" then u can target this cordlessdrill . com/makita-cordless-drill because Kw in URL Really help so that y. U can Just Create 1 page For That "makita cordless drill" and target this cordlessdrill . com/makita-cordless-drill to that page add some Good content related to your kw and Good Onpage for that Page work for u so u can get good ranking with in 2-3 Month.
Well, first i will check keyword competition in Google Adword tool and then choose the url. As my point of view cordlessdrill.com/makita-cordless-drill is good option for your site. It will help to get SERP in search engine.
The second one is best cordlessdrill . com/makita because it's look like search engine friendly url !!!
I think "cordlessdrill . com/makita" is good for SEO. Top label domain performs better than any other.