Personally of those that you list I have only booked with Cruises-N-More/American Express and had a pleasant and non-problematic experience. I recently found out that Mary, the agent I worked with is no longer there.
In weighing the differences I recommend looking hard at the following
Price, (make sure all taxes and fees are included) Perks such as OBC/On Board Credit, amount of deposit required, cancellation penalties and pay close attention to non-refundable fees. (these vary quite a lot) On the Cruise Compete website you can look at reviews of the agency. There will be a button to click in their response.

I advise that you stay clear of and DO NOT BOOK WITH ecruisestore.Com if they respond to your request for quote

On my last cruise, I took the lowest price w/the most
freebies offered. This is my modus operandi.

Call Ann Stilson at 888-800-1177, email her at cruisevacations@aol.com. We have found he prices to be the best and she will match any lower price if you find one. She has booked only cruises for 18+ years and before that was with NCL. She really knows her stuff. However she only does referrals, her past passengers and groups. She does not sit by the phone waiting for it to ring, she doen't need to. You have to tell her Bonnie from NC said to call.
Also try cruise.com - they have good prices too.

I book based only on price, and have used a few of your list, with no problems. Key factors to consider if booking with a price priority. Expect no "service", if you need "hand holdling" book elsewhere. You aren't likely to have a lot of detail to any questions. All you can expect is a valid ticket.

Always pay with a credit card, ALWAYs get the cruiseline booking number, and immediately verify DIRECTLY with the cruiseline, your booking. If any problems, get them fixed. Notify and dispute credit card charges IF you can not verify your booking.

I have been booking like this for 25 years, when you used to have to "call" discount brokers. Never been scammed in 62 cruises.

Excellent advice from Budget Queen. I would also use the feature in CruiseCompete where you can read reviews of the agency and (sometimes) see a link to their BBB info. Also, if you do have concerns, contact CruiseCompete directly. I've read online where they've gotten involved and helped to straighten out problems.

Thanks for the great tips, everyone. Fodorites always come through!

I'll incorporate some of the excellent advice here to help narrow down the booking options. I'm sure I'll have more questions once I get a little further along. It's wonderful to have a resource like this forum to turn to for advice.

Thanks again for the helpful responses!

Agree with hpeabody Do Not book with ecruisestore.com. We have booked with Best Price Cruises and Cruises-N-More. The only problem we have had with any on-line cruise discounter. is whan we bought insurance through them. Better to be safe and go to insuremytrip.com and buy straight from the ins. company

Ecruisestore is out of business.

OMG! Triathlete, I found the thread on Cruise Critic. I was one of their victims. I was double charged, they did not make my payment until several weeks after the due date, their whole M.O. I had used Amex and worked with them to get the double charge part straightened out and it was the 11th hour at 11:59 pm that Princess got my payment after several weeks of uncertainty trying to work with ecruisestore. It was one hell of a nightmare for me. I say GOOD RIDDANCE! to ecruisestore. What is happening right now was my worst fear at the time I was going through it. I feel so bad for their current victims and wish them luck and good future cruises

I've used cruisecompete for two of my cruises, cruises n more and Bontour travel. Going through cruisecompete I definately received the lowest prices. Just research the company and make sure you know what's included in the price. Good luck..

The quotes should tell you what is included in the price - be careful there because taxes, fuel surcharges, port fees may or may not be included and make price comparison not as easy as it looks.

Make sure cabin class is the same as well for same reason.

When we have used cruisecompete, a couple of times there was one really really low bid - others were all in same general price range. I passed on the really low one - figuring there had to be some reason for the great difference in price.

Several cruiselines (do not remember which ones) never really discount at all - on-line and other travel agents may give you a shipboard credit or something like that, but the actual cabin cost does not change. When that has happened, we just booked directly with cruiseline.

Gail: On lines that don't allow discounting (i.e., RCL and Celeb) you can get hundreds of dollars in onboard credit from the many agencies. Well worth booking with an agency rather than directly with the line.

I always purchase from Cruise Compete and save a couple of hundred $$. I have to, since I travel solo and the supplement kills me any place I search. My technique is
1 Get as much deck/cabin/price info from websites such as Vacations To Go and others
2 submit request on Cruise Compete. Make sure to fill into the comments section your state of residence; military?; age 55+.
3 call the ones with the best price and perks
note: make sure the cabin offered is NOT w/ an obstructed view since the lowest price usually reflects that.
There are web sites, like http://cruiseadvice.org which show the ships deck/cabin/cabin #'s as well as pros and cons of each ie close to elevator and stairs; below the pool or restaurant, etc. Hope this helps

If you only want to book based on price then pick the cheapest with the best perks and you'll be good to go. I have used some of these agencies and some were good and some were terrible when I had a problem and couldn't solve it. Most of these people have never even cruised! They sit in a house in Wisconsin and have never ever been on a cruise. Of course, I realize most can't have gone on every ship on every line but seriously? one or two cruises does not a travel agent make. I rely on customer service such as when that supposed on board credit just doesn't seem to make it to my cabin or when I have been waitlisted for a dining and just get told it is what it is. My real travel agent would tell me how to go about correcting this when I get on the ship. I am pretty well traveled and I have realized over the years that the travel agent doesn't charge any more than the cruise line and in some cases charges even less. Now that's a perk but the real perk comes when I am sitting on the tarmac and know I can't make my connection and I can actually text my agent at 11 pm and they will rebook or reroute me and have a text waiting for me when I land as to what to do. Ask your agent at Crucon or cruisecompete if you can call or text them at midnight for help. See what answer you get. Or better yet - try doing it and see if they answer the phone.