T7 is not BP. It is a synthetic substitute.
If you are asking about the best propellant for a muzzleloader, the answer will depend on the gun that you have.
Real BP is hard to find, because it is considered as an explosive. As a result, few dealers stock it. It is easier to ignite than the subs, but corrosive and dirty. As noted above, if you are using a flintlock, it may be your only choice as a pan powder.
In a caplock, you can use any substitute, except BH 209.
For .45 caliber, FFFG works better than FFG IMHO.
In an inline, you can use real BP or any of the subs, with the following caveat: BH 209 requires a gun with a closed breech, a short flash hole in the breech plug, a tight fitting sabot and a hot primer. You have to remove primer fouling from your breech plug's flash channel with a hand held drill bit every 20 shots or so. If you meet these requirements, it is by far the cleanest and best performing propellant for muzzleloaders.
If not, here is a rundown of the others:
Pyrodex RS: easy to ignite, cheap, consistent, dirty and corrosive.
Triple 7: slighhtly harder to ignite with #11 cap. OK with musket caps and #209 primers. Harder to clean than Pyrodex. Tendency to produce a crud ring. Corrosive, but not as much as T7. More potent than Pyrodex, so higher elocities. Consistent.
APP and JS

very easy to ignite. Easy to clean. Less fouling than Pyrodex and T7. Low and inconsistent velocities. Therefore: inaccurate.
APP and JSG sticks: Even more inconsistent than the powdered stuff!!
BH 209: Expensive (but less so than pellets). High and consistent velocities. Easy to clean. Cleans like smokeless powder. Non corrosive. Low fouling. Requires a hot 209 primer for ignition. Sensitive to flash channel fouling. Non hygroscopic. BH is my personal favourite in an inline, but it has its limitations, as noted above.
Black MZ: See JSG above.