a lot depends on latency too. I have one of every class, but due to rarely having lower than 150 latency, I tend to play ranged classes more. Witch hunters are great as are White lions, but can get bored at times in wb play, and sieges.
I always see a lot just sitting on their mounts, at a siege, instead of patrolling posterns paths, ganking those otw to keep, or sneaking up on the walls etc, some do, but a lot don`t. Small groups of Witch hunters groups of 2 or 3 same as White lions roaming the lakes can be a lot of fun.
There`s nothing wrong with those classes, try them and see what you prefer, they are good in Scenario groups too, for focusing down targets with assist train, due to high burst damage.
Engy is fun, but unless its changed recently, it still suffers from the same thing it had on live, High armor values in game, and most of it`s damage is dot damage, with long duration , and low damage ticks, that are easy to heal through.
They changed turrents some, to help with dot damage, to lower the duration of the dots, inorder to increase damage which helps some, and they added a armor debuff in rifle tree to help with single target damage. I haven`t tried them lately to see if it really helps, or if its just the same Fluff damage, easily healed through, and helps them build moral for moral bombs . Someone who`s still playing them actively now, can answer this for you.