Depends on your budget. The Michell Technoarm is about £500 and can support expensive MC carts (I have a Zyx R100H and it's a nice combo). At the high end of the spectrum you have the SME IV or V - the V being viewed by many as the holy grail (about £2100+). I'd expect most dealers would do you some discount. I have the Technoarm and it's very good but I still have the bug to upgrade to the SME at some point!
I have an old bronze edition Gyrodec with a gold SME V arm and the black arm mount from the Orb. Saw the gold SME V on the Orb at a show when it was first released. Knew I'd have to get one and eventually I did. Looks and sounds stunning. Carrtidge is a Ortofon Kontrapunkt B.
I have an SME1V on my Orbe - I preferred it to the V when auditioned, but cannot remember the details.. Cartridge is a Te Kiatora Rua into a Tom Evans Groove. Lovely, and worth every penny, especially as it was all very lightly used second hand !
On my old Gyrodec I had an Origin Live arm, which was also pretty good way back then, but the Orbe/SME is so much better (as it ought to be !!)
It is sonically excellent but like most parallel trackers it looks a bit of a botch job. It also requires you to site an air pump and other machinery somewhere adjacent to it. If your Gyro is a plinth unit with a lid, you won't be able to close it.
Given the Gyro will work with just about any 9" arm you want, your choices are endless. The SME options are lovely if a bit pricey. I don't like Rega arms or the Tecnoarm so went for a Roksan Tabriz which sounds excellent and it beautifully built. I use a Dynavector DV20X (low output version) with good results.