Whether you decide to fill or not is determined by the final finish you are trying to achieve. If you are trying for a high gloss you don't have any choice but to fill. Also, with regards to waterborne finishes. Some of the waterbornes out there do not play nice with white oak. Check with the mfg before using them or you may be in for a dissapointment.
You may consider using a good sanding sealer before coating (make sure it is compatible with urethane) This will help fill the pores somewhat and let you build your finish quicker. Also, may provide you with a sufficient barrier coat for a waterborne finish should you go that route. Most sanding sealers as with solvent based urethanes will give you an ambering effect as will some waterbornes (GF EnduroVar is one I use) but you can also get "water clear" or "ultra clear" in the waterborne finishes.
General finishes puts out some very good products that will give you great results. Shoot them an email their customer service is very helpful.
Also, you might email Jeff Jewitt at Homestead Finishing he has helped me out quite a bit in the past.
Good luck