I've used both, Tren E is a smoother ride, but the compromise is the results... they're smoother too. It's still Tren and will build you... but Tren E is less crazy.
Tren A is a beast. The sides can be tough, depending on quality and dosage and because of the short ester, the Tren absorbs fast which means your sides come hard and fast and you just have to ride it out if you dosed too high. Ask me, I have lots of personal experience.
That said, if you've been doing AAS for a while, eventually you find yourself facing off with Tren. I won't really consider a cycle without it.
My recommendation these days would always gravitate to Tren A, and build your dose slowly (50mg eod) If your product is exceptional, you might not get much higher than 100mg eod before the sides get too unpleasant. But the physique Tren will give you is tight and second to none.
Do have an anti prolactin on hand. Tren can kill your sex drive and grow you tits fast and it's NOT estrogen based... So you can eat Letro like M&M's and it's not gonna help. My fave is Prami, others like Caber. Try the reseach labs for decently priced accurately dosed anti-progestins.