Pair Original Sierra-1s with which Atmos/Surround speakers

Hi all! I have 3 of the non-upgradable Sierra-1 speakers: Left, Right, and Center. I also own a Rythmik F12 subwoofer which is amazing. My AVR is a new to me Onkyo RZ50 which I am very happy with! Dirac Live has done a great job to my ears.

I'd like to expand my 3.1 system to 5.1 in the near future, then to 5.1.4 in the medium future, so I'm planning out the next speakers to buy, and want someone to help me decide what the best path would be. Usage is 60% HT and 40% Music.

Option 1: Move the Sierra-1s to the rear (ditch the center) and purchase new L/C/R Sierra LX or EX. Get some Klipsch reference or ELAC Atmos speakers.

Option 2: Get the highly regarded ELAC Debut 2.0 for LCR, and move the Sierra-1s to the rear (also ditching the Sierra-1 center). Get the ELAC atmos speakers.

Option 3: Keep the Sierra-1s up front and get Elac Debut 2.0s for surrounds, and ELAC atoms to match.

Budget is somewhat an issue, and 1 is very expensive, 2 is medium, and 3 is cheapest. Which do you think would sound the best for me?

Personally, I'd steer clear of any of those "up-firing" ATMOS speakers. When I was researching ATMOS for my upgrade, that method was a distant third. First was on/in-ceiling, 2nd was high on-wall (about 90-95% of on/in-ceiling), and upfiring bringing up the rear. Due to my room, I went high on-wall (front and rear).

Personally, I'd go with either the LX or EX for LCR. Maybe leaning towards the LX for HT although I do love the RAAL tweeter. Or, keep the S1's, depending on your budget.

Further, I'd look at the HTM200s or CBM170's for surrounds, particularly if keeping Sierras up front. For ATMOS, depends on where you are placing them. The HTM200's work really well for ATMOS duty (and surrounds - I use them for ATMOS and used to have a pair as surrounds).