If you realy need the specialized tool, Sthil is certainly a solid brand. But I'd suggest taking a long look at a large split boom powerhead + attachment.
I believe Stihl makes a gear head attachment rated for a blade. With that, you can put lots of other toys on the powerhead.
I have a Stihl Kombi. That's the Stihl split boom weedeater that takes attachments. When I bought it they had a small 2 stroke version, and three 4-stroke versions. The 4 strokes all weighed the same, and were separated by $20 in price. The price bumps bought more power without adding weight. So I got the most powerful one. I love it. I've thought about buying another to have one at both properties.
Stihl will tell you its not compatible with the cheap/unniversal "click link" attachments, but the generic attachments work just fine for me.
The Stilhl Kombi attachments have an extra bump on them, so they won't fit a generic powerhead. But a generic attachment will go in a Stilh Kombi powerhead. Just be sure to get it all the way in, or it will ruin the shaft (so I've read, never done that myself).
I will never own another weedeater that isn't split boom. Its one engine to maintain. I get that for pro lawn care guys, having every specialized tool makes sense. They'll use them all plenty to keep them running good. And the slightly lower weight and specialized construction is worth it for them. But for me, one powerful engine and a pile of attachments is perfect.
Sometimes I buy stihl attachments, sometimes I buy generic. Off the top of my head, my attachment list is: string trimmer, blade trimmer, blower, edger, chainsaw, hedge trimmer. Only the string trimmer and blower are Stihl. I've never seriously used the blade trimmer, so I can't comment on that (I don't remember where I got it, I've had it decades).
Sometimes I specifically prefer a cheap attachment. I'll take more risks with a cheap attachment, and get more work done faster than using an expensive attachment I don't want to break. A couple years ago I bent & ruined a $40 chainsaw attachments. But I got a challenging job done much easier by riskig the tool. I also swapped out the bar and chain with a longer one. The Kombi motor runs a 12" bar fine, and the gear box hasn't blown yet.
This may not be appealing to you, but I've been very pleased with powerful high quality powerhead and a mix of quality and budget attachements.