So much choice, but if you are looking for shortish days...
Ben Challum is straightforward (though I prefer to make a circuit by going up the track from Auchtertyre and climbing the NW ridge).
The Tarmachan ridge is very worthwhile: the short (but unpleasant) scramble is entirely avoidable, though this is not obvious going anti-clockwise - if you reach the top of the tricky part, go back uphill for 20-30m and look for a faint path heading off on the N side. Going clockwise, the bypass path is obvious, heading up left as you approach the rocky section.
There are several options on the Lawers range: Ghlas - Lawers - Corranaich is a nice combination, and you can opt out of the last hill if you have had enough.
You could just do one of Dorain and Dothaidh if you don't fancy both:
https://www.walkhighlands.co.uk/argyll/beinn-dorain.shtmlBeinn Odhar on its own is a reasonable option for a short day, as is Meall Odhar just to the south of Tyndrum.
Stob a'Choire Odhair (with Stob Gabhar) is also a reasonably short day with decent paths.