In the USA, the Denon remote costs $110-$120, and it undoubtably will provide the best operation of the 4306.  www.usa.denon.com/ArchivedAVReceivers.asp  has a list of all the functions the remote can perform, and the associated codes.  I count roughly 120 functions using the Denon IR protocol.  I think it is unlikely that you will find any universal remote which supports all of the functions directly.  Probably some programming will be required.

Even $20 universal remotes can control the 4306, but such remotes won't have a button labeled, for example,  "Dolby",  or "Rear channel volume", etc.   A touchscreen remote which is highly programmable can probably provide a reasonable user interface, but I suspect the cost will be much higher than the Denon remote, which is also touchscreen.

Among cheap universal remotes, those made by UEI (typically sold in Europe under the brand name OneForAll) are the safest bet, because any of those manufactured in the last 2 or 3 years can control every function of the 4306, using setup code 1360, either out of the box, or by user programming, without needing to learn from the original remote.  [I can provide the details if you are interested.]  But unless you only want to typically control a few functions, I think it will be very hard to remember which buttons are associated with the functions.  Actually I find that I rapidly become satisfied with a particular setup of a receiver, and then I only use a few functions, like volume and input selection.

I think you'll be happiest withth Denon remote, unless you plan to use a universal remote to control other components.