Well, considering you are not the most experienced player(due to 2 80s 1halfmeeleish) i would give guardian a look aswell! Yes its kinda "basic" but that isnt always bad you know. Think of it as an old car, you have what you need and nothing more. Also thoes things you have are very, very strong. Like counterweight 10% bonus crit chance and 2sec cd. Still gains fatalityes on assassins above 50%.
As for pve also guard is the toughest! And has most h8. Last i checked thatd what you need to tank
When it comes to DT and Conq you might see that i play conq. Yes i love the conq and i think its the best class. I will list some pros and cons below:
DT
Pros:
-may deal loads of dmg(tali specc mgc armor)
-funny ways to chain abilityes to gain Max out come
-good cc when feated.
-good healt regen
Cons:
-Many random procs that may or may not apply as you want.
-Very slow, easy to get away from
Conq
Pros:
-Can be played in very many ways due to its good AA Perks and vert different feats.
-Can also deal alot of dmg iffeated for it(carnage<3)
-A good arsenal of different ccs
-Some healt regen
-challenging and might be a bit hard for less exp players.
Cons:
-unlike with DT you can't have too good dps and still be tough.
-very many conqs around so i recomand going carnage as its not too many carnage conqs.
-because of the brute bullds OPness many players will whine about you playing an OP class even if you play as carnage. There usualy isnt a that big difference between speccs and some peeps then think the class is OP when it actually is a perk used by brute conqs(battlefield commander)