Yes at least torx bits for the 1/4" drive.
Sometimes I use T50 T55 or even T60, but that's pretty rare (for example I think you need that if you want to change steering wheels).
And normal hex bits. Even the rare 7mm. That one is sometimes used for the holding screw on disc brakes. (I dont have a bit/socket but it's in my allen wrench set)
I think you have to look at the functions you have to perform.
As 'basic' functions I regard:
- complete oil/fluid change
- change sparkplugs
- change wheels
- change brakes (pads and discs)
-change lights
These are tasks to 'keep the car running' (even if xenon lights nowadays last as long as a pair of shocks)
For everything on wheels, undercarriage and brakes I recommend a torque wrench from a safety pov.
So for this you want a good jack, axle stands, fluid tray, 1/2"+1/4" socket set (with allen&torx bits, extensions for both 1/2 and 1/4, 1/4" hand driver etc), combination spanner set (if it's only to hold the bolt from the nut you're loosening with your socket set

) and a 1/2" torque wrench (about 40-200Nm). And of course screw drivers, pliers, hammer, maybe a chisel&punch set.
Remember everything on the undercarriage/brakes is heavy, strong and stuck. So having loosened a bolt completely doesnt mean you can take it out. Sometimes it needs a wack with a punch from the other side.
If you look at combination sets (toolboxes etc) be sure you get one with a 'full set' regarding the combination spanners. Most toolboxes/cases have with an incomplete combination spanner set. That for instance 16mm and 18mm are missing (like that halfords 114piece set). I can tell you right away that your bmw really is filled with 16mm boltheads, so that set is imho useless on that point.
If you want more, you're going to get pullers and stuff, and variants on what you have, so an extra allen key set or torx key set because you cant always reach in tight places with allen sockets and a ratchet.
Or a 14mm allen key to change your diff fluid etc. There's no such thing as too many tools.
As for quality the sockets, spanners pliers and screwdrivers need to be of decent quality. You use them a lot and they'll last you a lifetime.
As for pullers and other tools you don't need all the time, you can buy cheap chinese stuff on ebay (maybe not the cheapest ones) and if they fail replace them by branded tools. It's of no use to buy some expensive kukko pullers immediately without knowing you'll use them or abuse them.
At least that's how I do it. The difference in price between chinese and german stuff is huge.