For this sort of character, I like features such as "Bonus Help" and other "lazy warlord" features --- the character ends up enhancing the overall combat effectiveness of the party, even if in narrative terms, he's not out there smiting and slaying and so forth.
Ok, like I know I've been over this a lot, but I'll give it one more go. The Mastermind, if he uses the Bonus Action Help a lot, and really the main Action Help, like, almost ever, is not "enhancing the overall combat effectiveness of the party".
That's exactly the point I'm trying to make here - if you want to
increase the "overall combat effectiveness of the party", definitely do not be a Mastermind, because the Help action, used to grant Advantage in combat, but at the cost of your action economy, is typically going to
reduce the "overall combat effectiveness of the party", when used from a Rogue class chassis.
Lazy Warlords were totally different. You typically had a mediocre at-will attack, which you would give up, in order to cause another PC, with a much better attack, to make an attack. Thus the overall combat effectiveness of the party
increased.
Advantage isn't worth anything like an actual attack. Even a relatively low-damage attack (i.e. without Sneak Attack) is usually worth more than granting Advantage. Advantage, when you actually calculate how much it's helping, often translates to 1-4 damage (effectively, over time). This is why True Strike is a totally terrible cantrip whose only genuine use-case is casting before you try to Plane Shift someone (as discussed at extreme length in another thread).
There's no non-caster that can do "Lazy Warlord" or "enhance overall party combat effectiveness without attacking" stuff in 5E. There just isn't. It's not in the rules. Battlemaster Fighters can play at being a Warlord, but only the non-Lazy kind - they have to attack to activate Commander's Strike, for example (so at 5th an above must necessarily still make attacks).
If as was discussed earlier, you could grant your Sneak Attack to another (this was possible in 4E and possibly also 3E, I note), things might start looking pretty different.