I have used Advantage several times in the past. Unfortunately they are very similar to other companies in trying to upsell you to higher car categories (that they would give you free anyway since they don't have your category available), trying to sell you all the optional coverages, etc.

The main difference I noted with Advantage compared with the larger companies is that they charge your credit card at the beginning of the rental for the full value of the rental. Not sure if you would get a credit if you happened to return the car earlier.

I would rent with them again. I just always check my rental contract with any company before signing it to be sure rate is correct, optional coverages are appropriately declined, etc.

Generally I have had very good experience with National for one-way rentals. You might want to try them for the fun of it.