You can ask your realtor for the title/escrow fees from different title companies and be able to see what is charged. They are normally pretty close. Sometimes there a little 'junk fees' that can be eliminated but there is not a major difference when you consider the total costs inolved in buying a house. However, every little bit helps. Your contract will reflect which fees you are responsible for vs. the other party.
The other factor which is more a consideration in this current market is the factor of who gets to pick the title company in the first place. If you choose to buy a bank owned property, they often insist that you use their title company. They may not accept your offer if you insist on a different company.
While who is selected to do the title and escrow, is always an item for negotiation in a real estate transaction, more often than not, the party paying the fees in the purchase transaction want to select the title company. But again, it's always negotiable in who gets to select the title company, and you can always ask for any adjustment in fees that you are responsible for paying.