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If you want to take a TS themed army, the Black Legion Cabal formation is basically a must.

Lord-Sigil, MoT, Bike, <weapon of choice>
Ahriman
2 units of chosen, stuff, rhinos.
3 units of 5 marines, Flamer, Meltabombs, Rhino w/ Dozer
3 Bikes, 2 Melta's
Las preds, Vindicators, Maulerfiends.

Cabal Detachment
3 Sorc-Lv 3, Familiars, Bikes, Sigils if you want em. All roll Biomancy until they get Iron Arm and/or Warp Speed with there Force Ax, then shreiks and such.

Put the Lord with the bikers and the Cabal. Infiltrate Ahriman and a unit of Chosen with shooty stuff. Plasma guns?
Add in some extra Rhino squads, but leave off the TS Marines. Paint your CSM blue, call it a day.

That's one of the worst "Thousand Sons" themed armies I can remember seeing (at least it doesn't have Nurgle marked units in it). Having Ahriman and 3 sorcerors without the MoT doesn't make for a Thousand Sons theme, doubly so when you advocate not actually taking any Thousand Sons! Yes, I know they're terrible, we all do, but it's not really a TSons army without them is it?

Thousand Sons are most definitely my favorite army.
Finding a reliable way to play them while remaining true to the 'fluff' can, however, be challenging.
I know that it is anecdotal evidence, but here is a rundown of an 1850 list which I recently used in a game against a very experienced opponent who was playing ad mech.

Cabal formation: 4 MoT sorcerers on discs- 1x biomancy, 2x telepathy, 1x sanctic. All level 3. All with sigil & spell familiars

CAD: Chaos Lord on disc. MoT, PF&LC sigil

MoT level 3 sorcerer w/familiar, sigil, disc, biomancy, meltabombs

3x min Thousand Sons squads.

5 spawn (unmarked)

I got life leech, warp speed, smite, and endurance on biomancy. Got shrouding, terrify, dominate, and shriek on telepathy, got sanctuary and cleansing flame on sanctic. MoT powers were inconsequential (unsurprisingly.)

Discs joined the spawn. Between feel no pain, IWND, and life leech, the unit just kind of kept regenerating. Shrouding on the spawn and 3++ on the characters made the unit very tough to deal with. The sons just sort of shuffled along behind the cabal pouring fire into any units which looked likely to counter assault or shoot up the cabal after the assault.

Opponent conceded at the top of turn four.

Now, the cabal & lord & spawn star came in at a hefty 1400 points, making it possibly the most points inefficient Death Star in the history of 40k.
I realize that there are far more efficient / effective ways to do this sort of thing, (Daemonkin khorne dogs and bikes are a thing) but I like to play fluffy regardless of the cost.

It worked in this case though. Would it work more than once? Probably not if they knew it was coming.