Craigslist is hit or miss. I find that unless its Fender, Gibson or PRS people generally don't know what it is and the item won't sell as quickly. Ebay is by far the easiest way to sell with global reach, but between Ebay and Paypal, you get hit for fees that can total 15% of the sale price, cutting into your profit. Also, when I tried to sell my Ultra on Ebay last year, I was surprised that Ebay wanted my credit card #. Its for their buyer protection. Basically, as I understand it, the buyer can return an item for most any reason. I felt this opened up too much opportunity for abuse. I'm not a big box retail store, so I'm not able to offer quite the generous return policy they do. I do my best to accurately describe the item and make sure the buyer has a happy experience, but its too rife for fraud.....the buyer could damage the item and demand a refund, have buyer's remorse or simply demand a refund and ship me back a box of rocks.
On Craigslist, I get the impression that people are gear-rich and cash-poor. I always get lots of trade offers, some good and some not so good ("Hey, will you take this stack of guitar magazines from the 80s for your American Standard Strat?"). And then there's the hassle of flakes, people who waste your time who don't have the money anyway, and people who want you to deliver the gear 40 miles for half your asking price.
I've had the best luck advertising on forums that cater to the customer base. For instance, after 3 weeks of nibbles, trade offers, etc. on Craigslist for my AxeFX Ultra, I put it on the For Sale forum here and was inundated with great offers on day one! Of course, everyone here knows what the AxeFX is and I get the impression are mostly serious buyers!