Generally, if you want dependable classes for both PvE and PvP, I’ve found the soldier classes – Guardian and Warrior – to be the strongest. Thief also seems to be fairly strong in PvP, but I’ve struggled a bit in some PvE with it in areas where the soldier classes breezed through.
I know this isn’t the answer you’re looking for, but almost every class can do both exceptionally if you take the time to really hone your skills with it. I thought mesmer was terrible and weak until I really gave it a stronger go, and then I enjoyed the class.
But, in general, Guardian is going to be the most stable class, both in terms of balance and consistent ability. In PvE you can put out enough DPS to solo well, and in PvP you can make a bunker build, which allows you to hold capture points well and support your team that way. It’s the class I eventually settled with as my main for those reasons.
