Hi OP, I just had this whole dilemma to deal with and really did a lot of research and tried a whole lot of violins. My DD used a Gliga up to Grade5. Gliga's can be good instruments, bu aren't set up properly (unless you buy them at a specialist string shop), so will definitely need at the very least a new bridge and possibly some neck work. Also, they are wildly inconsistent.
The advice I got over and over again for advanced grades (Grade 5+) is invest in either a hand made or antique violin, and don't stint on the bow. I was surprised at how much a decent bow was, but as a rule of thumb if you've got a good violin you should think of about 1/3 of the cost again towards a bow. We tried both carbon fibre and pernambuco bows, and eventually settled on the Coda Prodigy Bow which is carbon fibre and fantastic.
The big decision for me was choosing between an antique violin or a modern (hand made) Chinese one. Good antique violins arguably hold their value better, but there's a lot of crap antique violins out there. I was a bit sniffy about Chinese violins at first, and the more I found out and the more we tried, the more I leaned towards them. The other upside of a modern violin was we could take advantage of the Assisted Instrument Purchase and save the VAT, which saved us a ton of money.
It was really important that there was a good trade-in policy, and specialist advice and service I could trust. Eventually I dealt with Cardiff Violins (ask for Cecile) who were fantastic helpful. Cardiff is nowhere near me - I dealt with everything online and over the phone. We have a beautiful violin and bow that makes an incredible sound.
Oh, and don't be afraid to try more than one violin "on approval". Good luck!