I use/ have used Rodgers, Alessi, Reischl, Robson, Gotoh Premium, Sloane.
Rodgers Alessi Reischl Robson Gotoh Sloane
1. Mechanic A + AA A AA A AA
2. Esthetic AAA AA A - A A B
3. Durability all excellent (10+ years easy)
4. Service AA A n/a CCC n/a n/a
5. Replacement easy easy n/a n/a very easy n/a
6. Precision all excellent
7. Price can be obtained form the net
The above is based on my judgement. Others may find it differently.
Rodgers turns very easy (something like driving a Toyota), but the rest is like driving a European car. Reischl if not maintained regularly, is extremely hard to turn. To solve this, I clean and apply WD-40 with cottonbud everytime I replace the strings. Once cleant and applied with WD-40, it turns smoothly and feels much lighter. Robson is one of finest, but it is extremely difficult to communicate and unresponsive. Rob Rodgers is very charming , accommodating and responsive. I have 4 Rodgers. The oldest one is 32 years (attached to my Kohno No.50 circa 1981) and is still working well.
Another finest tuning machine is made by Jorg Graf, the brother a very fine luthier Oskar Graf. I don't own this Graf tuning machine, but by judging its look, it is at par with Rodgers. Mechanically, I have no words on that.
But there are other fine tuning machines costing easily above $100 which I have no knowledge on i.e. Graham Macey, Exagon, Fustero, Gilbert etc.
All of my guitars have premium tuning machines. I think tuning machine helps to enhance the apperance of the guitar. It is like a car with a sport wheel. It looks fast even driving slow.
Masaru Kohno No.50 - 1981
Yamaha GC 71 - 1984
Gary Southwell - 1997 ex. Julian Bream - a bench copy of 'Hauser 1940'
Oskar Graf - 2000
Fritz Ober 'Hauser 1' - 2007
Richard Brune 'Fleta 1956' - 2011
Andrea Tacchi 'Bouchet' - 2014