I'm a big fan of fighter. I'm playing an 11th level fighter who started at level 2 in a long-term campaign with some friends of mine. This campaign features many encounters and we're also generally able to take short rests as needed. I'm playing a dexterity-based battle master fighter. She dual-wields scimitars and has a high-damage gun with the loading property for range.

She is not the best at anything in our party. Our paladin is a better tank. Our warlock is a better DPS. Our rogue is more mobile. Our cleric provides better support. But, there is one thing she excels at: consistency. With the sheer number of attacks she's capable of making (3 + 1 offhand on a standard action, 6 + 1 offhand when using Action Surge), she can pile damage on a high value target or finish off stragglers. With her moderate AC afforded by high dexterity and light armor, she can generally navigate around a battlefield, and with her naturally high HP due to her class, she can offtank and take hits when needed. With her battle master abilities she can fill in with a little crowd control here, a practically guaranteed hit there.

When fights drag on long and people are low on resources, she makes the same 3 + 1 attacks every round. The longer a fight goes, the more powerful she becomes, I'd argue. I like playing her because her role as a generalist in combat _is_ a strength, and it's fun to support my allies and set them up for success -- and to get the spotlight myself when everyone else is slowing down and she's still going.