Try everything. When I rolled an engineer, I used P/P up to level 20 or so and got bored pretty quickly. I set him aside for a couple months, came back, and experimented with some rifle builds and have been hooked ever since. With that said, I have been finally tinkering with some pistol/shield builds after all this time and find those to be very fun and challenging.
People have different experiences, but I have a level 80 thief and guardian and neither one really grab my interest like the engineer. Many will probably disagree, and that’s fine, but my advice is to experiment with all of the weapon combos (rifle, P/P, P/S) as well as all of your utility skills, even if they seem meh or boring in the description.
For what it’s worth, I mostly PvE due to a hectic work schedule, but I dabble in WvW and sPvP as well. I find engi to be lots of fun and plenty capable.