A Realtor is going to compete for listing opportunities as well as for sales.  You should not feel bad about comparing proposals.  But like anything in life, it is not always about the price.  If Agent A tells you everything you want to hear, lists for the highest price and asks for the lowest commission in return, that may actually be the poorest selection to make.

You should ask for a marketing plan.  What has the success rate for your type of home been for each agent?  How did the agent determine the optimal list price for your home?  Remember that the optimal list price is not the amount you 'want' or 'need', it is the price which should result in a fair offer in a relatively short exposure time to the market.

The agent with the most business sense and suggestions for you  to do things to make your home show better should be the one you select.  If you are on the middle of a 5 mile suspension bridge, you do not want to be thinking that it was built by the low bidder.

As with any major purchase, it can only benefit you to compare a few options before moving forward.  When choosing a real estate agent, you are purchasing their services to sell your home.  You should be comfortable with the person you choose, they should provide the services you deem important , and you should be satisfied with the cost of those services.

That being said, remember the phrase, "Buyer beware."  If you base your decision on the agent that quotes you the highest selling price and/or the lowest cost, you may not be getting the best deal.  In this competative market, some agents will try to entice you to pick them by telling you that they can sell your home at a high price.  Imagine you were the buyer; what would it take for you to pay extra for a house?  Other agents will charge you very little, but you will want to inquire about what services are they providing (and what services they are not providing).