Pretty much exactly what ELS said. Most people feel that Tren Ace is better or "Superior" because it kicks in way faster. Ace you can start seeing a difference in a week atleast in strength gains where Tren E can take to about 3 weeks. Also Tren Ace is preferred because many people have many side effects that really suck biggest in my opinion is Rediculus Insomnia.
Since the drug is out of your system faster these side effects can be diminished much faster as well. But the only difference between the drugs is active life span and the ester weight of the drugs. The bigger ester E takes up more room than the smaller ester in the oil solution.
But, 1000mg of Tren E is pretty much the exact equivalent of 800-900mg of Tren Ace could be more specific but, don't remember Ace Ester Weight right off hand. Also, because E is a heavier slower drug it allows for less pinning while blood levels still remain rather stable. Ace because of the smaller ester honestly needs to be shot atleast EOD but, to really stay stable and see less sides it needs to be daily where Tren E can be pinned every 3-4 days with little consequence.
So in short I run Tren E over Ace because I don't want to pin daily so it is just a convience thing for me. How ever if I was running a faster ester Test just for simplicity and convenience I'd run a faster acting Tren.