I have a 700 Remington that is getting worn and rusty from years of hard use.

I am ready to get it coated but only whant to do it once.

What's the best....Black T....Bearcoat....or what?

I haven't used either of the coatings you mentioned but...I've had a couple rifles Cerakote'd and like it well enough.
If I were to do another one I would look closely at one of the Robar finishes. I have heard some good things about them, perhaps someone can chime in with some first hand experience.

http://www.robarguns.com/precision_coatings.htm

As far as price, durability, complete corrosion protection, good looking, known product that's been a round awhile,

check out Black T........

I'm only going by my past research, I have no first hand experience with black T.

I got my very first experience with coating today...did a Duracoat myself on the metal of a rifle...its "curing"...looks good...so far...so good...

Robar

Nothin wrong with cerakote either.

I threw on some flat tan on the ol' 243 barrelled action today, we'll see how it holds

Oh yeah... it's this new super expensive proprietary coating blend called Krylon Camoflauge... hehe.

I have gunkote and cerakote both are holding up well.

I have several rifles with Black-T, two shotguns and some knives that were Black-T coated. One of the advantages of Black-T is that it is very thin and very flexible making it a good match for parts like trigger springs and firing pin springs also. The rifles I've had coated were coated everywhere except the bore and chamber providing complete corrosion protection. It is also slicker than snot and bolts slide like they were on ball bearings after coating.